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Chapter Text

“Master Regulus!”

He burns. Everything burns. Fiendfyre is rushing through his body, consuming him from the inside out. The flames lick at his throat and he scratches at it, claws at his own feverish skin, desperate for some release.

“I’ve never belonged here, Reg, you know that. I can’t put up with their bullshit anymore. I don’t want to be a Black anymore.”

Water— he needs water.

“Master Regulus, stop!”

He cannot remember why his eyes are closed, nor can he bring himself to open them. They’re sealed shut, seared shut by the flames. He thought his magic would protect him, like those witches who had burned at the stake, but his magic, too, has abandoned him. Perhaps his fears have come true. Perhaps he is a squib after all. 

“You will not see him. You will not speak to him. You will never utter his name again, do you understand? He is not your brother. He has never been your brother. He is nothing to you.”

His hands grasp at the rough, jagged rock beneath him and he remembers the cave. He remembers the darkness. He remembers the lake— water. Why is he sitting on a rock when he could be drenching himself in the lake to extinguish this fire? Stupid Regulus. Soft, stupid little Regulus, about as useful as a flobberworm, never able to think for himself. 

“No, Master Regulus!”

The water is cold, icy cold, but it does nothing to quench his fever. The fire has consumed his lungs, his throat. It licks at the back of his throat and fills his nostrils with its acrid stench.

“Look, there’s Sirius with the Potters! They’ve always been inseparable, haven’t they? As close as brothers. Closer, even.”

He wades further into the water. He submerges himself up to his neck and feels the water lapping against his jaw but still it’s not enough to stop the burning. Seaweed tickles at his skin and he jerks away, repulsed, only to find more at his back, hooking into his jumper, tangling in his hair.

“Master Regulus!”

Oh. It isn’t seaweed. 

Seaweed doesn’t have fingernails. 

“There is no need for fear, Regulus Arcturus Black. You are among comrades; brothers-in-arms. You will achieve greatness. You will make your ancestors proud. You will restore dignity to the House of Black.”

He panics. He thrashes. But the seaweed— the things , grip him tighter. Their long, sharp fingernails tear into his clothing and pierce his skin. They yank his head back. They grasp any part of him they can reach, dragging him down, down, down. 

“MASTER REGULUS!”

The burning intensifies and he tries to shout out, to scream for help, but his mouth fills with dirty lake water and dirty lake fingers choking him, drowning him.

“There are terrible things in the water, Master Regulus. Dead things, made alive again by terrible dark magic.”

He remembers. But it is too late. He scrambles for purchase on something, anything, but his scratched and bleeding hands only connect with sloughed skin and cold bones. He kicks his feet and connects with a ribcage, only to be gripped again by another vice-like hand. 

He knows it is too late. He knows he cannot fight them.

One boy cannot overcome an army of the dead. 

“Trust me, mate, you wouldn’t believe me if I told you.”

His head was throbbing. His stomach felt as though it had been pounded with an entire league’s worth of bludgers. His skin was sore and itchy all over and his throat . His throat burnt like he had swallowed the sun. 

“I don’t know. I don’t think so.”

That voice… that voice sounded exhausted but familiar. Too familiar. And it was accompanied with the lingering smell of stale cigarettes, those ridiculous French cigarettes that Sirius always smoked because he thought it made him more interesting and— oh Merlin, no.

“Prongs, c’mon. Just give me a few days.”

Heavy boots on wooden flooring pacing up and down. Awful tinny music. The voice and the cigarettes - it was Sirius, no doubt about it. Had both of them died? Mother would be furious. 

“I know. I know . Alright. Give Lils a smooch from me.”

Regulus flexed his fingers and found that he could still move them. They were cold, but he could feel the cheap polyester sheets he was lying on and he shuddered. The mattress beneath him was lumpy, a metal spring was pressing against his hip bone, and his cheek was suffering atop a hard, flat pillow. 

This was not what he had planned for. 

“Yeah, yeah, I can’t help being the favourite. Catch you later.”

Curiosity overcame him and he blinked his eyes open. Daylight was seeping in through thin curtains too short for the window they were supposed to conceal. The room was small, sparsely furnished, with peeling wallpaper and a stained carpet.

He rolled over onto his back to see the cracked, yellowing ceiling plaster and groaned. 

“Reg?”

Sirius was there at once, looming over him with brows creased in concern. He looked as though he hadn’t shaved in a day or two and his clothes were more wrinkled than ever. Regulus frowned at his unkempt appearance. 

“Here, reckon you’re alright to have some water now? Don’t want you spewing it up again.”

The softness, almost tenderness, in Sirius’s voice was utterly alien. Regulus couldn’t summon the strength to resist when Sirius hooked his hands beneath his armpits - he was sore, so sore, sore all over - and haphazardly lifted him into a sitting position, resting against the metal headboard. 

Sirius squeezed a pillow behind his back but Regulus wasn’t sure why. Those pathetic lumps could hardly make it any less uncomfortable. 

“I—” Regulus began, but his throat was full of knives.

“Shut up, just drink.”

Regulus was in too much pain to refuse and allowed Sirius to hold the glass to his lips. He drank greedily; the cold water was a balm to the scratchy itchy burning in his throat and he only scowled a little when Sirius tipped the glass too far and dribbles of precious water escaped out of the corner of his mouth.

“More?”

Regulus gave a jerky nod - his head still throbbing with every movement - and Sirius gave him the sort of smile one might bestow upon a sickly child, before he disappeared down the narrow hallway Regulus could just about glimpse through the open door. He could hear his brother clattering about, then a running tap, and shifted against the headboard to try to make himself more comfortable. 

His arms, he realised, were covered in bandages. He was wearing someone else’s pyjamas, worn soft with age. And the locket— the locket was nowhere to be seen. 

“Where—“ he croaked, as Sirius returned.

Sirius hushed him, placed the glass to his lips once more, and Regulus drank though his stomach was churning and his heart was racing and he felt sick, sick , because what if he had lost it? What if it had all been for naught? Where was Kreacher?

“Another?” asked Sirius.

Regulus shook his head, a movement that sent needles of pain stabbing into his brain. Sirius sat back on the edge of Regulus’s bed and turned the now-empty glass over in his hands. The silence was uncomfortable, broken only by the strains of the terrible excuse for music that Sirius had always liked to listen to, drifting in from another room in— in whatever form of hell this was. 

It didn’t take long for Regulus to visually search the room, small as it was, but he could see no sign of his belongings. No sign of the locket.

“Where— where is Kreacher?” he asked, his voice rasping and grating against his throat.

“Grimmauld.”

“Is he— is he alright?”

“He called me an ungrateful brat and you his dear little Master so yeah, I’d say he’s fine.”

Regulus slumped down the headboard in relief, his fingers curled around the thin polyester sheets. He wished Kreacher had stayed long enough to make the bed more comfortable or conjure up Regulus’s own pyjamas from his dresser back at home. He wished he hadn’t gotten all stupid and sentimental and left his wand at home for Mother to—

Merlin. What would she think had happened to him? What had happened to him?

His heart thumped loudly, thrashing against his ribcage like a hatchling trying to break out of its egg. 

Did hearts still beat in the chests of the dead? Those dead things in the cave - he wasn’t able to suppress a shudder at the memory - had no hearts, but they were inferi, the darkest magic, wholly unnatural, abhorrent… 

“Am I dead?” he whispered.

“What?”

“Am I… is this hell?”

Sirius looked as though he were stuck someplace between furious and delighted, the warring emotions fighting it out in his sparkling grey eyes. Regulus’s eyes had never sparkled, had always been dull, everything about him had always been dull in comparison to his brilliant, sparkling brother. Sirius’s mouth twisted, and he let out a bitter bark of a laugh.

“No, Reg, this isn’t hell. Welcome to my home.”

“Your— oh.”

Regulus had the courtesy to look embarrassed, but he was embarrassed on Sirius’s behalf and not because of his own blunder. This was no place fit for a Black. He wrinkled his nose, his eyes darting to the too-short curtains, the dented and water-marked bedside table, the haphazard stacks of books beneath the windowsill. 

“But…” Regulus said slowly. “I thought… I thought that I had died.”

Sirius looked at him with something akin to pity. “No, not quite. You’re made of stronger stuff than you look.”

“And… you’re sure this isn’t hell?”

This could be a trick. A test. Surely even Sirius wouldn’t be so proud, so determined to refuse any knut that had come from a Black - because Regulus knew that Uncle Alphard had left him a sizeable sum in his will, and oh hadn’t Mother been furious at that - that he would stoop to living in such a… a hovel as this. 

“A hovel? A hovel ? I save you from the brink of actual fucking death and you decide to thank me by calling my flat a hovel ? Cheers, Reg.”

Oh dear. He must have said that out loud. 

“You are such a little shit. I swear to Merlin, if you didn’t look so sickly and pathetic— did it ever cross your mind that I chose to live here? That I like it here?”

“But…” Regulus said, wrinkling his nose again. “It’s so… primitive.”

“Oh I’m sorry ,” Sirius said, exasperated, throwing his hands up in the air. “Should I add some fucking snakes? Would that make you feel more at home? Snakes and— and dark shit, and bloody Phineas commenting on your every move?”

Regulus couldn’t summon the energy to do more than blink at his brother as he fumed and stomped and brandished his wand, turning the bedcovers from a garish brown-and-orange pattern to deep Slytherin green, transforming the ends of the bedposts into coiling serpents’ heads and the lamp on the bedside table to match. 

“I draw the line at painting the bloody family crest on the wall,” Sirius said, pointing his wand at Regulus. “You can do that yourself, you little prick.”

Regulus thought that if Sirius was willing to go to this sort of effort for him he could at least make the mattress more comfortable, and said as much.

“Oh for fuck— you are insufferable !”

He didn’t hear the rest of Sirius’s insults. Feeling drained, he wriggled back beneath the third-rate bedcovers and fell soundly asleep. 

Water. Water everywhere. Water in his eyes and water in his ears. Water filling up his nose and his mouth and he can’t breathe - he can’t breathe - because there’s water everywhere.

Grasping hands clutch at his legs, twisting, scratching, tangling him up in a jumble of limbs that don’t wholly belong to him.

He shouts, and someone shouts back, but help doesn’t come. Help never comes.

He screams and thrashes about, his throat rasps and he’s going to be sick. He thrusts out an arm and his hand lands on hair - long, tangled, human hair - and he screams again, trying to yank his fingers away.

“GET OFF, REG! Stop trying to fucking scalp me!”

Regulus’s eyes snapped open and his screams faded away to a whimper. 

His heart was pounding, his breathing rapid, but he was warm and he was dry. He wasn’t there, in the cave. He was in the uncomfortable bed in Sirius’s awful hell-adjacent flat but he wasn’t in the cave. No dead things were trying to drown him, here.

“Didn’t realise you had such a death grip,” muttered Sirius as he rubbed the sore spot on the top of his head.

Death grip.

Regulus stared at his brother in horror.

“Where is the locket?” he asked, the words tumbling out of him.

“With the rest of your stuff,” Sirius said with a shrug, as though he wasn’t talking about a sacred relic, a Founders’ heirloom, a vessel for a fragment of the Dark Lord’s soul. “Bit gaudy, isn’t it? Not your usual taste.”

“Give it to me.”

Sirius raised an eyebrow. “Don’t worry, I’ve not stolen it,” he said. “It’s not really my thing. Might be worth a few sickles, though… reckon old Borgin’d take a look? I could use the silver to buy a new pair of curtains up to Little Lord Reggie’s exacting standards.”

“I’m not joking, Sirius. Give it to me,” Regulus demanded, bristling at Sirius’s teasing tone.

He tried to sit up and shift himself so he could get out of bed and find the locket himself, but his arms were trembling and he couldn’t support his own weight. Weak. He’d always been weak. He resorted to frowning at his infuriating brother instead.

“Alright, keep your knickers on,” said Sirius, standing with his hands raised, palms facing outward. “I’ll get your stuff. Don’t move.”

Regulus didn’t try to move; couldn’t move, even if he had wanted to.

The flat was small and Sirius soon returned with a surprisingly neat pile of folded clothes - the ones he had worn to what he had thought (hoped) would be his death - and there, sitting atop a soft maroon jumper, was the locket. 

Regulus snatched it as soon as it was in reach and looped it over his head, his fingers trembling. It felt warm to the touch and lay heavy against his chest. It was dark magic, the darkest magic, created through unthinkable means. He knew that, he knew it, but it still felt comforting, somehow. The way it pulsed against his sternum, matching his own heartbeat, brought him relief. He sunk back against the lumpy pillows and sighed. 

“Is this— it is !” Sirius said, sounding oddly joyful. “This is my jumper!”

Regulus closed his eyes and turned his head away. If he had known that Sirius would discover that particular fact - that he had wanted something of his brother close to him when he had gone to meet his doom - then he wouldn’t have bothered with it at all. He would have worn Mother’s nightgown or— or Father’s smoking jacket, or anything. Anything . 

“That’s adorable, Reg.”

“Shut up.”

“Honestly, I’m touched. I never knew you felt that way.”

“Shut up .”

“It still smells like me! Did you charm it? You soppy little thing.”

Regulus groaned, pulled the bedsheets fully over his head, and pretended to fall asleep.

The nightmares were as frequent and unwelcome as summons from Grandfather. 

Most often Regulus would wake in a choking panic, reliving over and over again the visceral feeling of being near-drowned. His limbs ached and itched as phantom claws scratched phantom lines down his skin. His head throbbed, his throat burned, his stomach churned.

Sometimes it felt like he was drinking the potion all over again. Snape’s work, he suspected. A potion that conjured nightmares and fears and one’s worst, most terrible memories.

During these times Regulus found it difficult to distinguish his hallucinations from reality. He couldn’t tell if he was five or twelve or eighteen. He couldn’t tell if he was in Grimmauld Place or Hogwarts or Voldemort’s chosen lair or Sirius’s run-down flat - nor could he decide which would be worse.

But Sirius was there, every time. He wasn’t exactly a soothing presence, but he brought water and blankets and occasionally managed to turn Regulus’s sobs into a laugh.

No, Sirius asked too many questions to be entirely soothing.

He wanted to know what happened to Regulus, who had hurt him, why Kreacher hadn’t taken him to St Mungo’s or back to Grimmauld Place. He wanted to know why Regulus refused to take off the locket, and what significance it held. He wanted to know why Kreacher was so adamant that Sirius keep Regulus’s presence in the flat a secret. That he keep the fact that Regulus was alive a secret. 

And most awfully, most shamefully, Sirius kept asking about the thing on Regulus’s left forearm.

Regulus suspected that Sirius knew he was (had been?) a Death Eater. Regulus suspected that Sirius suspected that Regulus knew that Sirius was in Dumbledore’s group of vigilantes. Regulus didn’t yet know how those two things could be reconciled, so he pretended to fall asleep whenever Sirius’s questions became too much to bear.

Sirius didn’t like this, but there was much about Regulus that Sirius did not like and he would just have to learn to live with it. 

“Honestly, Reg, I’m struggling to imagine the scale of disaster here since you once described knocking over a meringue at Narcissa’s wedding ‘the greatest catastrophe that has ever befallen wizard kind’.”

“It was terribly embarrassing,” Regulus sniffed. “But I suppose this is more disastrous than that, in the grand scheme of things.”

“Right. And whatever you did means you can’t go back to Grimmauld?” asked Sirius.

“No.”

“And you can’t contact your friends?”

“No.”

“So what, you’re just going to stay here indefinitely?”

Regulus shifted uncomfortably in the rickety chair and stared glumly into the dregs of milky tea at the bottom of his chipped mug. It was a far cry from the fragrant Darjeeling he would have drunk from a delicate teacup at home but then again, everything about Sirius’s flat was different and strange.

“Reg?”

He sighed. “This isn’t where I had planned on being, afterwards.”

“No? So what did you plan?”

Regulus tugged at the sleeves of Sirius’s maroon jumper - cleaned and repaired by Kreacher, apparently, after the horrors it had encountered at the cave - and pulled them down over his knuckles. The scars and bruises littering his skin had mostly healed, thanks to a surprisingly well-stocked medicine cabinet in Sirius’s bedroom.

“Come on, Reg. You must have had something figured out. You turned up here practically dead, you—”

He could almost hear the sickle drop. And though he was still staring stubbornly into his tea, Regulus knew exactly the look Sirius was wearing. He had never been one to hide his emotions; he had always been his mother’s son.

“You idiot! You fucking idiot! What the hell could be so important or disastrous or whatever you want to bloody call it that you were planning to fucking die for it?”

Regulus couldn’t speak. He curled in on himself, his shoulders hunched up to his ears and his arms wrapped tightly around his chest. He wanted to shrink, to be invisible, to be gone . If he had died in the cave, as he had planned, then he wouldn’t have had to sit in this stupid flat and listen to his stupid brother’s stupid questions and worry about when the stupid Mark on his stupid arm would start burning again. 

Sirius began pacing again. The kitchen was small, and the little floor space there was didn’t seem to make for satisfying pacing, but he was pacing all the same. And shouting. Shouting at Regulus, shouting at Mother and Father, shouting at the entire bloody world.

Regulus couldn’t bear it. He stood, suddenly, sending the rickety chair clattering to the floor. Sirius stopped, mid-rant.

“Where are you going?” he demanded.

“I’m— I’m tired,” Regulus said, his voice cracking.

He hurried into Sirius’s spare bedroom and buried himself beneath the sheets. He curled into a ball, squeezed his eyes shut, and prayed that he would not be disturbed. 

“I’m not eating that,” he said in disgust, physically recoiling from the bowl Sirius had brought into the room.

“What’s wrong with it?” 

“It looks like something Grandfather Arcturus would feed to his plimpies.”

“Don’t be so dramatic,” Sirius said, sighing quite dramatically as he shoved the bowl under Regulus’s nose.

“Why’s it so… lumpy?”

“I dunno,” he said, prodding at the gruel-like substance with a spoon. “It’s good for you. Eat it.”

“I don’t want to.”

Sirius sighed and set the bowl aside. “Fine. What do you want? Something from the pie and mash shop?”

“The what?”

“A jellied eel?”

Regulus frowned, unsure if his brother was making fun of him or not. “Are you asking me to make you a potion? Because I’ve been here for days now and have yet to see a cauldron.”

“No, you idiot. You need to eat something that isn’t toast.”

“Let me call Kreacher, then, if you’re so concerned about my diet.”

It was an old argument by now. But Sirius’s cooking was appalling and Regulus didn’t know a frying pan from the back-end of a mooncalf so the brothers had reached something of an impasse when it came to food.

“I’m not having that wrinkly little prick in my home any more than is necessary.”

“Fine. Then I’ll have some toast, please .”

Sirius huffed and rolled his eyes but dutifully retreated to the kitchen. Regulus settled back against the sofa cushions and pretended to read his book, a cheap dog-eared paperback he’d selected from the pile in Sirius’s spare room. Something muggle. A ‘classic’, it declared itself. It wasn’t much, but it was a better form of entertainment than the odd brown box with garish talking pictures that Sirius was so obsessed with. 

He returned with a plate piled high with toast and flopped onto the sofa next to Regulus. Regulus grumbled and tucked himself further into the corner, away from Sirius’s disgusting hairy toes - why couldn’t he wear slippers like a normal person? - while he delicately nibbled around the burnt bits of toast and tried not to let his eyes wander to the television screen.

It didn’t take long for Sirius to grow bored. He reached over the back of the sofa for a battered old guitar and began strumming aimlessly while the television still blared. Regulus had forgotten how noisy Sirius could be.

“Please stop offending my ears,” he said archly.

The guitar was missing a string and was terribly out of tune, but Sirius didn’t seem to care. He just played it even louder. 

Regulus huffed and was about to retreat to the spare bedroom when there was the unmistakable sound of a key turning in a lock and both brothers stared at each other in horror.

“It’s only me,” a voice called out from the hallway.

“Shit,” Sirius muttered. 

He threw the guitar aside with almighty clang that had Regulus wincing and covering his ears, and bounded to his feet.

“You home, Pads?” called the voice.

It sounded closer. Sirius swore again. He looked, panicked, between Regulus and the living room door.

“I’ve got the post - any idea why we’ve been getting letters addressed to— oh. Hello, Regulus.”

Regulus remembered to breathe again. It was only Lupin, Sirius’s bedraggled friend from school. Odd that he would have a key - odd that Sirius hadn’t mentioned that someone could drop by at any moment. At least Regulus was dressed appropriately for visitors. 

“Sirius,” Lupin said, quite calmly. “Care to explain why there is a Death Eater sitting on my sofa?”

“You’re back early!”

Regulus raised an eyebrow. His brother’s voice was too high, too cheerful. Sirius was rocking himself on the balls of his feet and had positioned himself, quite deliberately, between his friend and his brother. Regulus, still nibbling at his toast, peered around Sirius’s frame to watch the conversation. 

“No,” said Lupin. “I said I would be gone for nine days, and it has been nine days. Again, I ask, why is there a Death Eater in our home?”

Our home . Ah. That might be an issue. 

“He’s not a Death Eater,” said Sirius. “He’s just my brother.”

“You don’t know that. You haven’t spoken to him in months. Years .”

“He was hurt, what was I supposed to do? Let him die?”

“Maybe.”

A heavy silence fell. Regulus did not like how they were talking about him as though he weren’t there, and he certainly didn’t like the casual way Lupin suggested his death. He realised, as he watched them, that Lupin had changed. He was thinner, more bedraggled, more scarred. Regulus was in no doubt that Lupin, too, had joined the war. That Lupin had reason to want Regulus and his friends dead. 

“I would never do that,” Sirius said. “I would never—”

“I assume Dumbledore knows about this?” Lupin interrupted.

Regulus crept up from the sofa while they were talking and stood directly behind Sirius. Still slighter than his older brother, still a head shorter, Regulus tugged at the back of Sirius’s t-shirt; he turned, and Regulus shook his head, his eyes wide. Dumbledore couldn’t know. Dumbledore would find a way to wheedle any useful information out of him and then discard him, cast him aside, leave him for the Dark Lord to find and punish and kill, slowly, painfully, just as Dumbledore had abandoned all the Slytherin children who were supposed to be in his care.

“Why are you here, Regulus?” asked Lupin.

“He’s in trouble,” said Sirius.

“What sort of trouble?”

“I don’t know, exactly, but—”

“You don’t know,” Lupin said. He sighed, pinching the bridge of his nose, looking far older than Sirius. “Of course you don’t. Sirius, you have to tell Dumbledore.”

“No!” Regulus yelped. “Sirius, please .”

“It’s alright. We won’t. Not yet.”

“Sirius, there is a Death Eater in our flat. I know he was your brother but he is a Death Eater. We have to tell Dumbledore.”

“No, Moony. He is my brother and he was a Death Eater. He defected.”

Lupin’s hard eyes fell on him again and Regulus curled his fingers around Sirius’s arm.

“You defected?”

Regulus nodded. 

“And how, may I ask, did you do that?”

“I… did something.”

“Something big,” added Sirius. “Very big.”

“Right,” Lupin said sceptically. “And you don’t think that Dumbledore needs to know this something very big ?”

“Please stop talking about Dumbledore,” Regulus begged. “Please.”

He couldn’t stand it. He couldn’t stand the panic rising in his chest, the way Sirius looked at him with pity and the way Lupin looked at him with suspicion. He couldn’t stand the thought of having to face Dumbledore, of having to tell him everything , of being judged and cast aside like he was nothing. He knew he was nothing. He didn’t need to be told that fact by Dumbledore, of all people.

Regulus fled, brushing past Lupin as he darted back into the hallway and into the spare bedroom - or was it Lupin’s bedroom? He locked himself in, leaned his back against the door and slumped down to the floor, burying his face in his drawn-up knees. 

The walls in the flat were thin, and he could hear them arguing. 

“You’ve got to tell Dumbledore.”

“Did you see he was wearing my jumper? Cute, right?”

“That was my jumper, Sirius.”

“No, it’s mine. I must’ve left it at Grimmauld, and Reggie went looking for it. The big softie.”

“It’s my jumper. You stole it off me. You always said you liked how soft my clothes were, compared to yours, completely disregarding the fact that mine were soft and worn out of necessity, not choice.”

“No, I like your clothes because they smell like you, have been close to you, have—”

“Stop trying to distract me,” Lupin said, sighing heavily. “You’ve got to tell Dumbledore. Or I will.”

Somehow, Sirius managed to get Regulus a stay of execution. For a few days, at least, Lupin promised that he would not go running to Dumbledore. But Regulus knew that his time was short, that the grains of sand were spilling all too quickly through his hourglass. 

The atmosphere in the flat was uncomfortable, to say the least, but Regulus had spent his entire life in uncomfortable atmospheres and knew how to handle them by now. The flat was certainly not big enough for three tense men (Regulus still had to remind himself that he was, technically, a man now; it felt odd, even a year after he had officially come of age), so Lupin was spending most of his time away, working, he claimed, and staying at a friend’s overnight.

Regulus, unexpectedly, found himself missing his own friends. Had they ever been friends? Perhaps acquaintances would be a better term. Fellow soldiers. 

Lupin had arrived with a pile of letters addressed to Regulus. Evan, Finn, Barty, and even Bash Lestrange had written, asking where he was, asking if he was hurt, worrying about him. Evan had written the most, at least once a day since Regulus’s disappearance. Each of his letters was more frantic than the next, his handwriting erratic and slanted, each word spilling over into the next until it was barely decipherable. 

He hoped they weren’t suffering on his account. Because of the mistakes he had made.

Two letters were from Bellatrix. Regulus read those last and kept them beneath his lumpy pillow as a reminder. She was furious. He could feel her anger radiating through the parchment and suspected that more than one pile of ashes, the remainders of a howler, had been left behind at the post office. She threatened him with a multitude of punishments: fingernail removal, scalping, amputation, disembowelment, combustion, a plain old Avada Kedavra to the heart.

He glanced at the Mark on his arm and thought, with some level of detachment, that amputation would perhaps be worth considering. 

If he removed his arm, and the Dark Mark with it, then that would lay his most pressing concern to rest: that the Dark Lord, on discovering that Regulus had gone missing, would attempt to summon him. 

Father had been trying to find a way to remove it, before he had died. Mother had said that his death was Regulus’s fault, and she was probably right. It was probably murder. It was probably a punishment for poking around in something he shouldn’t have been, on Regulus’s behalf. 

He wondered what Walburga was thinking now, cooped up in that big old house all by herself. He had always known, deep down, that his disappearance - his death - would likely destroy what little sanity she had left after so many tragedies and disappointments. Andromeda, Sirius, Alphard, Father, and now Regulus too.

But he had never considered that he might still be alive to think about her. To miss her, despite her many faults.

He remembered the last time he had seen her, the night he had thought he was going to his death. It was barely a week ago, though it felt like a lifetime. Walburga had barely moved from her position on the chaise longue in the drawing-room, reclining in the darkness, dark eyes darting over the family tapestry stretched out before her, its gold threads glinting in the light of a single candle. 

What would she do, when she realised that he was never coming home?

He worried for Kreacher. Kreacher was the only other living being in that house, the only one left to bear the brunt of Walburga Black’s rage and grief and madness.

He shouldn’t have done it. He had been a terrible master - a terrible friend. He should never have let Kreacher go back to Grimmauld Place. He should never have taken Kreacher to the cave with him. He should never have offered Kreacher to the Dark Lord in the first place, to endure that dreadful potion and those dreadful reanimated corpses and the darkness, the suffocating darkness.

He hoped that Kreacher, if no one else, could eventually forgive him his sins.

“Are you ready to tell me what that is yet?” asked Sirius, quietly.

Regulus lifted his head in alarm and saw his brother looking pointedly at the Dark Mark on his exposed forearm. He hadn’t realised he had been clutching it; he had been too fixated on the pair of pigeons cooing on the windowsill, wondering when - if - he would be allowed outside of the flat again.

He released his iron-like grip on his arm and tugged the sleeve of his jumper back down.

“No,” he said, eyes darting to the living room door. Lupin was in the kitchen, rattling around with some pots and pans and singing loudly off-key. His cooking was better than Sirius’s, at least. Almost palatable. 

“Reg,” said Sirius, and Regulus was aware of how hard Sirius was trying to keep his voice soft, calm, non-threatening. That knowledge alone was enough to make Regulus feel cornered. “Reg, I’m trying really hard here. But you’ve got to give me something. I can’t put Remus off forever.”

Regulus shrugged and chewed his bottom lip as he continued to stare stubbornly out of the window. One of the pigeons fluttered its wings and flew away into the grey sky, leaving the other to peck for scraps on the windowsill. 

“It’s to do with You-Know-Who, isn’t it?”

Regulus froze. He couldn’t even bring himself to nod. He wished he were a demiguise and could disappear at will. He wished the sofa cushions would devour him on the spot. He wished he were anywhere but here, anyone but himself, doing anything but this . 

“I recognised the symbol. It’s the same one the Death Eaters leave above a place where they’ve… y’know. Done a murder.”

Regulus knew. He’d been there. He’d witnessed the Death Eaters’ atrocities, had participated in them. His reluctance to take part and his regret and shame afterwards could not absolve him of what he had done. Nothing could absolve him of what he had done.

He didn’t want to think about how Sirius might know about morsmordre . It was one thing to suspect that his brother was involved in the fighting, and another to see Lupin’s scars and overhear their murmured conversations about ‘missions’ and ‘the Order’.

They thought they were clever, using muffliato to conceal their discussions and arguments, but they’d forgotten that muffliato originated in Regulus’s house, not theirs. And they hadn’t realised that the Slytherins deliberately leaked the charm but not its counter. They hadn’t realised that Regulus could hear everything they said, whenever he chose to do so.

“C’mon, Reg,” sighed Sirius, the frustration leaking into his voice. “Give me something to work with.”

“It’s the same symbol,” Regulus murmured. “He calls it the Dark Mark.”

“Can I see it?”

Regulus swallowed. His throat was dry. Drier than dry. He could feel his chin beginning to wobble. But Sirius’s eyes were filled with curiosity, not judgement; with his head tilted to the side he looked very much like he had when they were children, and the most terrifying thing in their lives was a baby jobberknoll they had found in the woods at the back of Aunt Cassiopeia’s house. It had fallen out of a tree, Sirius had decided. Twelve years later Regulus’s ears still ring with its death screams.

“Reg?”

Regulus gave a reluctant nod. He closed his eyes and shifted position so he could hold his left arm out to his brother for inspection. Sirius’s hand felt warm as his fingers gently clasped Regulus’s wrist, but Regulus still shivered. Sirius slowly pushed his sleeve up and hissed through his teeth when that dreadful brand was revealed.

“It’s moving ,” he said, awed. “Does it hurt?”

“Not right now,” Regulus whispered.

There was silence while Sirius inspected it, rotating Regulus’s arm this way and that. He felt cold, exposed. Vulnerable. His heart was pounding in his chest and his head and he had to resist wrenching his arm back and covering it up again. But Sirius grew too curious and his fingers moved and—

“Don’t!”

Sirius’s grip tightened and he yanked Regulus’s arm closer. “Don’t what? Touch it?”

“Don’t, Sirius, I mean it,” he said, panicking. “It’s— it’s connected to the Dark Lord.”

“ Connected ? How.”

Sirius’s tone had grown stern. Regulus gritted his jaw, blinked, and prayed that he wouldn’t break down and start crying in front of his brave, strong, irrepressible older brother. 

“ How , Regulus?”

“I don’t know, exactly. I— I don’t know if it will summon him if you touch it, but—”

“It will summon him? This— this tattoo will summon You-Know-Who ?”

“Not if you don’t touch it!” Regulus said desperately. “It’s a— a way for him to communicate with us. With his followers. It works both ways, he— he can summon us, too.”

“How does it work? When he summons you?”

“It… it burns.”

“And what happens if you ignore him?” 

Both Regulus and Sirius jerked their heads up and saw Lupin standing in the doorway, his arms folded, a grim expression on his face. He cut a formidable figure, despite the frilled apron he was wearing and his flour-dusted arms. 

“I don’t know,” Regulus admitted.

“How regular are his summons? Is he likely to reach out to you once he realises you’re missing?” said Lupin, stepping into the room. 

Regulus gulped.

“What I mean to say,” Lupin continued, “what I really want to know is, how big of a problem is this going to be?”

“I don’t know.”

Sirius’s grip on his wrist slackened and Regulus pulled his arm back, yanked his sleeve down and curled up in the corner of the sofa to stare at his knees.

He was an idiot. He knew he was an idiot, knew he should have told Sirius about the Mark earlier, knew it was a problem. A huge problem. But… a part of him had hoped that the possibility of being summoned would go away if he tried not to think about it too much.

And now he felt like his arm was a potions experiment gone awry, a cauldron waiting to explode and destroy them both. 

“Could You-Know-Who track your location through this… Dark Mark?” asked Sirius.

“I don’t know. I don’t think so,” said Regulus. He wished desperately that Lupin had stayed in the kitchen and wasn’t staring daggers at him from the other side of the room.

“You don’t think so?”

“I’ve never seen it used that way - people have gone missing before, but a— a body usually turns up, sooner or later.”

“Right!” Sirius said joyfully, slapping his knees. “Great - we’ll just get a body and transfigure it to look like you, and—”

“Sirius,” Lupin interrupted. “Where the hell do you think you’re just going to get a body from?”

Sirius waved his arm in the air, dismissing Lupin’s concerns. “I dunno, there’re loads of bodies lying around these days. Don’t you know there’s a war on, Moons?”

Lupin looked very much like he wanted to throttle Sirius for even insinuating that he might not know the extent to which the wizarding world was currently ripping its own throat out.

“It won’t work,” Regulus said, his voice trembling, his whole body trembling. “He’ll know, he… he always knows. He knows everything.”

“Not to brag, baby brother, but I’m pretty good at Transfiguration.”

Regulus looked at Sirius with wide watery eyes and shook his head. He didn’t get it. Sirius didn’t get it. It wasn’t a game , it wasn’t something to joke about. The Dark Lord had never been a laughing matter for those unfortunate enough to end up in his path. Nobody had ever survived going missing, defecting from his ranks before - and Regulus suspected that he had only lasted this long because of the weight his surname still carried.

If he knew - if he even suspected what Regulus had done - he would be there in an instant, swooping through the window in a whirl of black fabric, filling the room with that hateful green light.

No. It wouldn’t be that quick. There would be torture, first - mental and physical. He would make Regulus watch while he killed Sirius. If the Dark Lord did it himself at least it would be over relatively quickly, but if Bellatrix got her way… Regulus shuddered. And then he remembered.

“I left a note.”

“What?”

“In the— in the place. When I did the thing. I left a note.”

“What? Why ?”

“I don’t know!” Regulus said, the tears welling up and finally spilling down his cheeks, catching in his eyelashes as he tried to blink them away. “I— I wanted him to know it was me, who— who did the thing… I signed it with my initials, only my initials, but he’ll know it was me!” 

Sirius groaned and flopped back against the sofa. “Why do you always have to be such a petty little shit.”

Regulus sniffed, pulling his sleeves over his fists and wiping furiously at his cheeks but the tears came fast, too fast, and he felt like he was drowning all over again. He took a gulping, choking breath and felt a soft handkerchief being pressed into his hand. 

He looked up and saw Lupin’s blurry figure retreating a step or two to perch on the windowsill. 

“So let me get this straight,” he said, calmly. “You went somewhere and did something that has necessitated your defection from You-Know-Who and your hiding out here?”

Regulus nodded, Lupin’s handkerchief clutched tightly in his hand.

“But you can’t tell us where you went or what you did? And you were stupid enough to leave a note, wherever you were - a note which could be easily identified as coming from you?”

“Moony—“

“I wasn’t— I wasn’t supposed to survive!” Regulus yelled.

The lightbulb hanging from the ceiling flickered and sputtered. Regulus was standing, though he couldn’t remember getting up from the sofa. He could feel Sirius and Lupin’s gazes burning in the back of his head and he couldn’t stand it, he couldn’t stand them staring at him and judging him and wishing he weren’t there. He wished he wasn’t there.

He fled back into his bedroom, the door slamming behind him of its own volition.

“Enough, Sirius. We have to tell Dumbledore.”

“No. I promised I would give him time.”

“He’s had time. This is far beyond anything either of us signed up for - You-Know-Who could turn up on our doorstep at any moment!”

“He won’t be on our doorstep, Moony. He’s not going to knock .”

“Sirius, please.”

Another argument. Regulus sat on the floor, his ear pressed against the thin wall, eavesdropping. His fingers were crossed on both hands and his toes would have been crossed too if he had ever been able to do that. He was hoping, wishing, praying that Sirius would be able to hold out for a little longer. He couldn’t face Dumbledore.

“If you don’t tell him by the end of the week, I will.”

“No, Remus. You won’t.”

“No? What makes you think—”

“This is nothing to do with you. This is— this is family business.”

Regulus sat up abruptly and let out a gasp. Was this what an out-of-body experience felt like? Regulus was light as a feather, levitating; his heart had floated right over his mouth and he was tingling all over.

Family business.

Family.

Sirius still counted him as his family, after everything both of them had put each other through. It was the nicest thing anyone had said about Regulus in years. Possibly ever . 

“Family. Family ? You said you never wanted anything to do with any of them, ever again. Have you forgotten, Sirius? Do I need to drag Prongs here, to remind you what you were like, the night you left?”

“He’s my brother. He always has been. He always will be.”

“Regulus is an adult, Sirius. He’s not your responsibility.”

“Yes, he is! He always has been— don’t you see, Moons? This whole thing, the Death Eaters, everything , this is all my fault. The kid nearly died because of me . I left him there, in that hellish house, knowing full well what they were like and what they were capable of.”

“Pads. We’ve been through this. You couldn’t—”

“But I could! I could’ve stayed there, or I could’ve forced him to come with me - he’s only small, I could’ve bloody carried him out of there - I could’ve made an effort, at school. I could’ve written to him. I could’ve looked out for him, warned Dumbledore what was going to happen. I could’ve done any number of things, Moony.”

Regulus stared at the wall in amazement, as though he could see straight through it to his brother on the other side, to his brother speaking such wondrous, miraculous things. Silent tears ran down his face, bittersweet tears: if only Sirius had said something sooner. If only he had known this was how Sirius had felt. 

He vowed to tell Sirius everything.

Lupin was a werewolf.

Regulus stared at the pyjamas he had borrowed from a werewolf and felt disgusted, terrified, horrified. How could his brother live with a werewolf ? How could his brother not have told him that he was sharing a flat, sharing clothes, sharing food with a werewolf ?

He looked to the window and saw the near-full moon watching him, laughing at him. He didn’t need to see the moon to know its phases, of course - he was a Black, and a Black was raised knowing the movements of the sky as well as the planes of their own face - but he looked, nonetheless, as though he couldn’t trust his years of schooling.

Lupin was a werewolf.

Regulus laughed, a little hysterically. Remus Lupin . The Naming Seer must have thought she was being incredibly witty when she gave him the name Wolfboy Wolfish. What was his middle name? Wolfgang? Fang? Fenrir?

The bedroom door opened and Sirius appeared, frowning. “What’re you laughing at?”

“Nothing,” Regulus said quickly. Your friend is called Wolfboy Wolfgang Wolfish and he is a werewolf; our lives are a joke . 

“Right… well, just letting you know that I’m popping out tomorrow night.”

“What?” Regulus yelped. He couldn’t help glancing back at the bright moon. You cannot leave me with a werewolf !

“Just for one night. I’ve got a… thing. With Remus.”

“What…?”

Regulus’s heart sunk right through the floor. Of course. Of course, Sirius wasn’t bothered by the fact that he lived with a werewolf because Lupin had bitten him and turned him into one too. Wasn’t that what werewolves did? Maraud around, infecting others with their vile disease?

His face dropped. He pulled the bedcovers over his crossed legs with trembling hands as though the fraying fabric might protect him from their gaping jaws.

His brother was a werewolf. 

When had it happened? At school? Was that why… was that why Sirius had felt he had to leave home? Before Mother found out and had him put down? Did the Potters have some sort of… sanctuary , for teenage werewolves? Did Dumbledore know about this? Did he deliberately let werewolves into the school? How many others had been infected?!

Lupin had been a Prefect !

“We’ll be back by morning. Don’t worry, James is coming over in a bit to double-up the protective enchantments so you’ll be perfectly safe.”

“WHAT?!”

Potter burst into the living room in a cloud of acrid smoke, because of course he did. When had James bloody Potter ever passed up the opportunity to make a spectacle of himself? 

“Wow, I always forget how small that fireplace is,” said Potter as he picked himself up off the floor, vanishing the soot marks as though they were nothing. “Alright, lads? Oh - Baby Black! This is… wow. Okay. Cool! You good, Reg?”

Regulus blinked at him, silently seething. He sat as still as a muggle statue, frozen in position on the sofa. It took all his willpower not to reach for Sirius’s wand and hex the messy-haired, lanky-limbed idiot right in his stupid face. 

Sirius elbowed him in the ribs and Regulus turned, frowning. “What?”

“Don’t be rude,” said Sirius, raising his eyebrows.

“It’s fine,” Potter said breezily. “Lily says hi. Oh shit - she baked some scones for you, I forgot. I’ll chuck ‘em in the floo when I get back.”

Regulus directed his frown back towards Potter. He was sauntering about the living room as though it belonged to him, twanging the strings of Sirius’s guitar, picking up Lupin’s discarded books, twiddling the wires sticking out of the television box, taking a bite out of Regulus’s toast. A year out of school hadn’t made him any less infuriating.

“Where’s Moony? Resting?”

“Yeah, he—”

“Good, because I thought we could…”

He trailed off as Sirius shook his head frantically, gesturing in what Regulus assumed was supposed to be a discreet manner. They hadn’t yet realised that Regulus knew about the werewolf situation; he had played it extremely cool. 

“Ah,” said Potter, winking. A most disturbing action. “Gotcha. Well. Shall we get to it? I’m assuming Baby Black is the reason for all this extra protection?”

“My name is Regulus,” he said sourly.

“Yeah, kid’s done a runner,” said Sirius, ignoring him. “Guess he takes after his taller, wiser, more handsome brother after all.”

Regulus had forgotten how much he hated Sirius and Potter together. Potter changed Sirius, made him more… cocky. More irritating. As if Sirius wasn’t cocky and irritating enough without Potter’s influence.

He rolled his eyes and settled back against the sofa cushions with the Daily Prophet , trying to act as nonchalant as he could while his brother and his nemesis discussed him as though he wasn’t there. The newspaper was filled with stories of the latest Death Eater atrocities; Regulus had no escape. 

Lupin emerged from Sirius’s bedroom, looking more exhausted than he had before he had gone for a nap. Regulus supposed this was some sort of werewolf thing and watched him warily. One could never be too careful in the vicinity of a werewolf, even when the moon wasn’t yet at its fullest: he had heard that werewolves sharpen their human teeth and have a taste for human flesh outside of their wolfish form. Regulus would not take any chances. He had not survived retrieving the Dark Lord’s horcrux only to be devoured by a werewolf. 

The Gryffindors discussed Regulus and his predicament while they worked. They didn’t bother to use muffliato , apparently not considering Regulus important enough to do even that. Lupin reiterated his argument that they ought to tell Dumbledore and Potter agreed. Infuriatingly, Potter seemed to hold more sway over Sirius’s opinion than Lupin did, and Sirius started to falter. 

“Righty-ho,” said Potter, bouncing back into the living room. “Protective charms all done! You’re safe as houses now, Reg. No need to worry that little head of yours.”

Regulus sniffed. “I could have done them myself if Sirius would have let me use his wand.”

“Oh? What happened to yours?” asked Potter. He sat himself down on the sofa next to Regulus and Regulus shifted as far away from the idiot as he could, pressing himself against the cushioned arm. 

“He left it at Grimmauld,” said Sirius, stretching and yawning as he wandered in from the hallway. “Little memento for Mummy wasn’t it, Reg?”

Regulus felt his eyes burning. He had intended it to be a memento, of sorts. Something for Mother to remember him by… something of him to bury, since she would never have been able to retrieve his body, even if she had known where it lay. But he didn’t like the way Sirius said it so casually, so flippantly, as though it were a foolish thing, the action of a child. 

“What, you decided to do a runner from You-Know-Who without a wand? Weird,” said Potter.

Regulus huffed and picked up the Daily Prophet again, rustling the pages as noisily as he could, angling it so Potter’s stupid face was concealed.

“He was with Kreacher,” shrugged Sirius. “S’pose he thought he didn’t need to do magic himself.”

“Wait, your mum’s batshit old elf?”

Regulus lowered the newspaper and fixed Potter with a glare. “Kreacher isn’t batshit .”

“Don’t get him started on that bloody house-elf,” said Sirius, rolling his eyes. “I swear he’s half in love with it. C’mon, Prongs, I want to show you the garage before you have to run off back to the missus.”

“I’m not in love with Kreacher!” Regulus said indignantly. “You can respect someone without being in love with them - not that you would know anything about respect .”

Potter raised his eyebrows and, to Regulus’s great annoyance, chuckled. “Bit mouthy, isn’t he?” he said to Sirius. “Right then Pads, let’s go see this bike of yours.”

Bike ? Regulus frowned at their retreating backs and wondered what could be so interesting about a bicycle. He vowed to never give Sirius the satisfaction of asking him. Perhaps he would investigate for himself when they were all gone.

The night of the full moon was awful.

Sirius and Lupin left together, piling further evidence onto Regulus’s hypothesis that the wolf had infected his brother. He thought he had overheard that Potter would be joining them too, as well as that Pettigrew fellow. Lupin had infected them all. The audacity of it… Regulus hoped that Dumbledore was aware and that he felt deeply sorry for ever allowing such a dangerous beast into his school in the first place.

The hours stretched on, restless and tense. Regulus didn’t investigate Sirius’s bicycle. He didn’t sleep. He barely moved at all.

Every breath of wind that whistled through the buildings outside sounding like the howling of a wolf. Every rattle of the windowpanes, every mysterious clunking noise from inside the walls, every footstep heard from the other flats in the building, convinced Regulus that the wolf was coming for him. That the Dark Lord had tracked him down.

Or worse, Bellatrix .

Sirius had left him his wand - and given him a long lecture about using it responsibly, as though Regulus was the one likely to act irresponsibly - and he clutched it tightly in his right hand as he sat in view of the flat’s front door, a blanket pulled tightly around his shoulders to ward off his shivering. 

Sirius and Lupin came back just after dawn had broken. They both looked tired; both appeared to have a few fresh scratches. 

“Got into a bit of a scrape, nothing to worry about,” Sirius explained, yawning. 

They went straight into Sirius’s bedroom, together. Regulus returned to his and willed himself to fall asleep but all he could think about was a werewolf’s jaw clamping around his brother’s arm.

“Look, we need to come up with some sort of plan,” said Lupin over breakfast one morning. “We can’t just keep sitting around and waiting for something to happen. I think we should—”

“Tell Dumbledore. You’ve said,” Regulus grumbled as he pushed the fried egg off his toast with his fork.

“Do you have a better plan?”

“That ideally doesn’t involve you topping yourself,” Sirius added, unhelpfully.

Regulus shrugged and gave up on his eggs in favour of a strong cup of tea.

“Why are you so reluctant to go to Dumbledore?” asked Remus. “He’s the most powerful wizard alive - more powerful than You-Know-Who - he’s fair, objective—”

“To you maybe. To Gryffindors. Not to the likes of me,” Regulus muttered.

“Here we go,” said Sirius, turning his back to them to refill his mug from the coffee pot.

“It’s true!” Regulus insisted. “I’m a pureblood and a Slytherin, Dumbledore’s two least favourite things. He never cared about me at school. He knew that my friends and I were at risk, he knew what our family was like, at the very least, after you ran away… if he didn’t care about preventing me from being recruited, why would he care now that I am trying to defect?”

“I’ll vouch for you,” said Sirius. “Moony will too.”

Lupin didn’t look so sure about this and besides, Regulus wasn’t sure that he wanted to have a werewolf speaking in his defence.

“So Dumbledore will only believe me because you said so?”

Sirius sighed. “That’s not what I mean. Don’t be difficult.”

Regulus picked up his fork and poked at his eggs again. The runny golden yolks had stiffened as they cooled, had gone rubbery. He felt his stomach squirm. 

He didn’t trust Dumbledore. And he didn’t trust how much Sirius trusted Dumbledore, either. What was stopping the man from arresting him on sight? What was there between Regulus and a lifetime in Azkaban, aside from Sirius’s word?

He pulled at the chain around his neck and grasped the locket tightly in his hand.

This was what he had. He could tell Dumbledore about the horcrux, but who knew if Dumbledore would even believe him? And if he did… what was stopping him from taking that knowledge and arresting Regulus anyway?

He had done this alone for a reason. He had not told anyone else about his discovery for a reason . He needed to do this alone. He needed to see this through to the end, alone. Because he had to prove to himself, at least, that he was capable. Worthy. Something more than second-best.

“I’m not trying to be difficult,” he said. “It’s just… Dumbledore has given me no reason to trust him with my life.”

“He won’t harm you,” Lupin said carefully. “Because you will be useful.”

“Excuse me?”

“I’m sure you have information - names, motives, locations of future attacks - that would be vitally important to the Order. In fact,” he said, giving Sirius a pointed look. “I’m quite surprised that we haven’t received anything from you yet.”

“I will not be used to further Dumbledore’s agenda. Whatever happens will be on my terms,” Regulus said bitterly, stabbing at his now-rubbery eggs. “And some of those names happen to be my friends. We’re not all torturers or murderers. Not all of us wanted this.”

One evening, when Lupin was sleeping elsewhere, Regulus gathered his courage and told Sirius. 

He told Sirius how he had begun to piece together curious little turns of phrase that the Dark Lord would pepper into his speeches and conversations - talk of immortality, of life-long rule, of reaching further into the Dark Arts than any wizard had done before - and how he, eventually, with the help of some hideous, obscure, half-rotten books in Grandfather Arcturus’s library, discovered the existence of horcruxes. 

He told him about Kreacher, and the cave. How Regulus had sought to disguise his growing repulsion towards the Dark Lord by offering his house-elf in service - and what Kreacher had told him afterwards.

Regulus blinked back tears as he recounted, his voice and hands trembling, what he could remember of his own visit to the cave. Sirius gripped his knee, and Regulus realised that he was crying, too.

“This is all my fault,” Sirius sniffed, eventually. 

“It was my choice. Everything I did was my choice.”

“If I hadn’t left you there…”

Regulus gave a jerky shrug, his fingers twisting in the locket’s chain. It had grown hot to the touch. “What’s done is done. I just… I need to find a way of destroying the horcrux. Then the Dark Lord will be mortal again. Then he can be defeated.”

Sirius sighed and flopped back against the pillows, rubbing furiously at his eyes. “You’re just a kid,” he said, sounding incredulous. “You’re a kid .”

“I’m not a child, I’m eighteen.”

“You’re my kid brother. And you’ve… shit. I’m impressed, Reg. You’re a bloody idiot, but I’m impressed.”

“It was nothing,” Regulus shrugged, though he was beaming, glowing with pride. He felt warm from the inside out, from the tips of his toes to the ends of his hair. He had never stopped chasing Sirius’s approval and here, at last, he had it.

“S’pose I’d better give you something in exchange for that revelation,” said Sirius, sitting up straight again.

“A secret for a secret?”

It was a memory of a childhood game, an echo of a much-uttered refrain. Regulus had always been good at sniffing out family gossip, and Sirius had always been good at discovering hiding places. Together - a secret given in exchange for another - they had been unstoppable.

Until Granny Melania had found them squashed into the dining room cabinet trying to eavesdrop on some salacious gossip about their Prewett cousins, that was.

“It’s a good secret,” Sirius nodded, grinning widely. “The best. You’ll love it.”

The secret almost gave Regulus a heart attack. Sirius was a— well, Sirius was a dog . An enormous, hairy, slobbering dog. A dog that was wagging its tail so furiously it caused a breeze. A dog that had pinned Regulus down with its paws on his shoulders and was licking his face .

“Get off!” Regulus shrieked, trying to bat the dog away. “Sirius! Bad dog!”

Sirius turned back to his more usual, human form and rolled onto his back, clutching at his stomach as he laughed uproariously. 

“Your face,” he said, wiping away tears of laughter this time. “If only I’d had a camera.”

“You— you’ve got hair everywhere!” Regulus said, incredulous. “What— how ?”

“Animagus,” Sirius said, still laughing.

“Yes, I worked that out. When ?”

“Fifth year,” he shrugged. “James and Peter, too.”

The news that Peter Pettigrew, of all people, had managed to successfully complete the Animagus transformation at the age of fifteen was enough to drive Regulus half-mad. But as soon as he began complaining about how Sirius could have kept this a secret from him for four years he turned back into that stupid black dog and wouldn’t stop licking him until he grew quiet.

Sirius Black. A black dog. Naming Seers had a lot to answer for. How could they have gotten his own name so wrong? Little King. Heart of the Lion . It was all nonsense; he ought to have been named Stultus. Foolish Boy. 

Sirius stayed there all night until Regulus, exhausted from imploring his brother to turn back into something capable of human speech, fell asleep with his head resting on Sirius-the-dog’s fur. And there, cocooned in his brother’s warmth, he slept more soundly than he had in years. 

“How do you know what he’s saying is true?”

“Because I trust him.”

Sirius and Lupin were arguing again. About Regulus, again.

“Well, I don’t! How do you know he’s not, I don’t know, spying for—”

“Do you trust me?”

“What?”

“Do you trust me, Moony?”

“Well obviously, of course, I—”

“Then trust that I trust him.”

“It’s not as simple as that, Sirius, and you know it. How do you know he’s not being a typical Slytherin and just looking out for himself? How do you know that he actually wants to defeat You-Know-Who and isn’t just scared for his own skin because he’s gotten himself in too deep? How do you know he didn’t only come here because he had nowhere else to go?”

“You weren’t here when Kreacher brought him here. You didn’t see him half-drowned, broken, bleeding… you didn’t see him almost die , Remus. You’ve no idea what he’s been through—”

“Because you won’t tell me!”

Regulus trembled beneath his bedcovers, clutching the locket in his hand. He was terrified that Sirius would give in, that he would tire of defending his stupid baby brother, that they would decide he wasn’t worth the risk any more and throw him out onto the streets. 

Because it was true, he didn’t have anywhere else to go. He’d never had a friend like Potter, someone who would have taken him in, no questions asked… his friends’ families were too interlinked with his own, too worried about appearances and sticking with the status quo. He had never had anyone he could turn to, apart from Sirius. There was nowhere else for him to go.

“I’ve told you as much as I can, alright? He’s not even told me everything. The kid’s terrified. He’s convinced You-Know-Who’s going to attack him from one side, and bloody Dumbledore from the other. Just give him a bit more time.”

“He’s had time, Sirius. Plenty of it. Time is running out. You-Know-Who could summon him at any moment, and what the fuck are we supposed to do then?”

“I don’t know, Moons. I just… I don’t want him to hurt any more than he has already, alright?”

The days dragged by. 

Lupin spent more time away from the flat. Regulus was relieved that he didn’t have to keep watching the doors and trying to anticipate the werewolf’s movements.

But Sirius was loud enough for both of them.

Regulus couldn’t curl up to read a book or the newspaper without Sirius barging into whichever room he had chosen, clomping around the creaking floorboards in his stupid big boots, talking loudly on that damned mirror with Potter. His laugh was like a cacophony. He was incapable of speaking at a civilised volume. Everything, everything was too big and too loud.

When he wasn’t playing terrible music on his record player he was watching terrible things on the television box. Sometimes he did both at the same time and made it very difficult for Regulus to concentrate on a fascinating exposé into the lives of Mancunian muggles that the television box showed during the evenings. Sometimes Sirius decided to play his guitar as well - although ‘play’ was being generous. He sounded more like an erumpent crashing about the Divination Tower than any of those oddly dressed fellows he liked to watch on the television box.

Regulus had always been an introvert, especially in comparison to his brother. He had always enjoyed his own space, had always preferred his own company, would always have chosen to spend a night alone in his bedroom whenever given the opportunity.

But even he had his limits, and those limits were a week spent cooped up with Sirius.

He longed to get out . He longed to stretch his legs, to feel the wind in his hair and the rain on his face, to hear the voice of someone - anyone - that wasn’t his brash brother or his brother’s idiot friends. He longed to take a walk down Diagon Alley and gaze into the shop windows, to make judgements on the latest broomstick models and sip on hot butterbeer. He would have even been satisfied with gloomy Knockturn Alley, or a ride on the stomach-churning carts down to his Gringotts vault.

Anything to avoid having to stare at the same four walls and resist the temptation to cut off his own damned ears just for a bit of peace and quiet. 

Sirius, eventually, noticed his brother’s restlessness. They both knew that they couldn’t risk Regulus being seen in public but he suggested a trip up onto the rooftop. Regulus was furious that Sirius hadn’t revealed the fact that there was an accessible rooftop earlier, but not furious enough to refuse the offer. 

It was bigger than the rooftop at Grimmauld Place. They didn’t have to clamber through their bedroom windows and haul themselves up by clutching onto tiles; there was a narrow staircase, an old door, and then the London skyline spread out before them.

Regulus closed his eyes and breathed in the fresh air. He could hear the rumble of muggle vehicles on the streets below, a distant siren, muffled conversations rising up from people going about their daily business.

Sirius locked the door behind them and beckoned him over to the edge. They sat atop the low wall, legs dangling into nothingness, and Regulus tried to get his bearings. North London, he thought. He heard Sirius rustling about in his pockets and wrinkled his nose as his brother lit one of those foul French cigarettes.

He offered one to Regulus, who looked at him as though he were quite mad. Sirius shrugged and slipped the packet back inside his jacket pocket. 

“Who’d’ve thought it,” said Sirius, exhaling a long plume of smoke up into the sky. “Both of us escaped Mother’s grip.”

“A most disappointing generation.”

Sirius snorted. “Even more disappointing if you consider all five cousins: three traitors, a Death Eater, and a Death Eater’s wife. Unless Cissa’s got one of those Dark Marks too?”

“I’m not a traitor,” Regulus said quietly, frowning at his shoes. Sirius’s shoes. His own hadn’t survived the lake.

“No? You must still be a Death Eater, then. Should I push you off this ledge and have done with it?”

He shrugged. It wouldn’t be the worst thing Sirius had ever done.

“Don’t sulk,” Sirius chided, draping an arm around Regulus’s shoulder. “This traitor thing has its benefits, you’ll see. No more lectures from Grandfather for a start.”

Regulus thought that he should probably shrug Sirius’s arm away but he couldn’t quite bring himself to do it. The weight and warmth were comforting, soothing; the closest thing to a hug he’d received in years. Even the smell of Sirius’s cigarettes wasn’t enough to make him squirm away; it stirred up nostalgia. It smelt like home.

“Do you remember,” Regulus said, quietly. “When Uncle Alphard came back from China? That time when… before Andromeda…”

“Before Romy married Ted? Yeah, I remember. He brought you that puzzle box and you hid away in your room until you’d completed it. I didn’t see you for weeks. Why?”

Regulus looked at his brother and blinked. “Ted?”

“Ted Tonks, Romy’s husband. He… you didn’t know his name?”

Regulus shook his head and looked away again, sat on his hands and kicked his feet. He didn’t know anything. Nobody ever told him anything about Andromeda, not even Sirius.

Ted Tonks .

“Huh. Well, his name is Ted. Edward, really, but no one calls him that.”

“Have you met him?” asked Regulus, quietly, half-afraid that Mother would somehow hear him and swoop down to punish him for daring to even think about such a taboo subject as his disowned cousin’s muggle-born husband.

“A few times,” said Sirius. He stubbed out his cigarette on the ledge and reached into his pocket for another, pulling Regulus closer to him - his arm still around his shoulders - so he could light it. 

“What’s he like?”

“He’s cool. He’s got that Hufflepuff vibe, y’know? Friendly, mild-mannered, seems like he wouldn’t hurt a puffskein, but you wouldn’t want to mess with him. He’s got this great big laugh, like how an old tree might laugh. His brother’s a mechanic and he’s given me all these manuals and tools for my bike. Too laid-back, though. Let Romy get away with giving their kid a ridiculous Black name.”

Regulus had rested his head on Sirius’s shoulder but looked up in alarm at this piece of news.

“They have a child?” 

“Oh, shit. Yeah. Dora - Nymphadora , Romy insists on calling her. She’s six. She’s a metamorphmagus.”

Regulus took in a sharp inhale of breath. A metamorphmagus. A new generation of Blacks had been born - a half-blood, but a Black nonetheless. He has realised, by now, that Toujours Pur was never meant to be about blood. She was a Black, a half-blood, and a metamorphmagus. 

There had been rumours of the ability lying dormant in their bloodline for as long as he had been alive - longer, even - but he had never believed them to be true. He had always thought it was one of those boasts that Grandfather Pollux liked to bandy about to impress his friends at the Club.

Did he know? Did he know that his great-granddaughter, fathered by a muggle-born, was a metamorphmagus? 

Was that all it took to awaken the rare talent? Fresh blood?

“It’s kind of unsettling at first,” said Sirius. “She likes changing her hair to match whoever’s near her at the time. But when she has a tantrum she goes bright red all over, like Cissa’s cheeks after too much wine.”

Regulus couldn’t speak. Couldn’t move. Couldn’t breathe .

“Do you… do you want to meet her?”

Regulus nodded. He did, very much so. He had a baby cousin. He was no longer the youngest in the family. The weight of producing a future generation had lifted from his shoulders. 

Sirius wrote to Andromeda. She wouldn’t allow Regulus to meet her daughter, not yet. Regulus thought this was quite reasonable considering the last Andromeda had heard he was a Death Eater trying to kill people like her husband. 

But she would meet him. 

Lupin didn’t care to hide his views on the matter: he thought it a dangerous, foolish, pointless excursion. He reiterated that they ought to be telling Dumbledore, not gallivanting around the country, but didn’t he realise that Andromeda might hold the key to saving Regulus? That she was clever, resourceful, determined; that she embodied all the best qualities of both a Slytherin and a Black?

Sirius thought it would be fine. He reassured Lupin that they would only be outside for a few moments while they apparated to their meeting point, a park near Andromeda’s home - Regulus was quite disgruntled when Sirius had the audacity to check whether he could apparate or not - and what were the chances that a Death Eater would be lurking on their doorstep, anyway?”

“Quite high, I would imagine,” said Lupin, dryly. 

Potter burst through the fireplace in his usual dramatic fashion and jumped straight into the argument, taking Sirius’s side, as always. He didn’t see the problem with taking a little risk now and then. Of course he didn’t. When had James Potter ever had to risk anything - really risk anything - in his entire life?

“Do you want to borrow my cloak?” he said, sauntering back into the living room with his hands in his pockets.

Regulus scoffed. “It will take more than a mere cloak to conceal me from any Death Eater whose path we might cross. Transfiguration will suffice.”

“I’m sorry,” Potter said amiably. “I should have specified: do you want to borrow my invisibility cloak?”

“Invisibility cloaks are not infallible,” Regulus sighed. “If the Dark Lord should—”

“This one is,” he interrupted, leaning back against the wall, looking smug, his arms folded across his chest. “It’s a Potter heirloom. Been in the family for generations.”

Regulus rolled his eyes. Potter was being utterly ridiculous. Everyone knew that invisibility cloaks lost their powers over time, more quickly the more they were used. Demiguise hairs made for particularly weak thread: they had the power of invisibility, yes, but they frayed easily, they stretched, they became loose and lost their potency. Most invisibility cloaks were little better than a well-cast concealment charm. 

“I can tell you’re sceptical,” said Potter. “Why don’t I show you?”

He disappeared into the hallway and Regulus heard the crack of apparition. He shrugged and picked up his book again. 

“Did Prongs just leave?” asked Sirius, popping his head around the living room door.

“Yes.”

“What did you do this time?”

“I didn’t do anything! He said something about an invisibility cloak.”

Potter returned almost immediately and dropped a pool of weighty silken fabric into Regulus’s lap. He sighed heavily, disgruntled that Potter had managed to bend the pages of his book, but when he acknowledged the cloak, when he saw that it wasn’t any ordinary, run-of-the-mill invisibility cloak, when he felt the thrum of magic pouring off it, he froze.

“Where did you get this?” he snapped.

“Told you, it’s a family heirloom.”

“For how long? Where did it come from?”

“Dunno,” Potter shrugged, infuriatingly. “Dad gave it to me when I got my Hogwarts letter.”

“You received this cloak when you were eleven ?”

Regulus was aghast. This wasn’t a toy, a plaything… this was an incredibly powerful magical artefact! He could tell its power, just by looking at it. Just by touching it. He unfolded the cloak and draped it over his arm, watching in amazement as it completely disappeared. As his Dark Mark completely disappeared. That Potter’s father could just cast this aside to a child - to a child as idiotic and chaotic as Potter had been, as Potter was … it was unthinkable.

“Eleven, yeah. It’s come in handy, right, Padfoot?”

“I’ll say.”

Regulus rounded on his brother. “You knew about this?”

“Er, yeah?”

“Who made it?” Regulus asked Potter, sifting through his mind for a list of historical weaving houses. “Webb? Shuttlesworth? Spinnet? Loomermann? Wynde?”

“Dunno.”

“When was it made?” asked Regulus. He was running the cloak through his fingers, inspecting the craftsmanship, the seams, the pattern on the fabric, anything for a clue as to its providence.

“Dunno,” Potter repeated. “Like I said, my dad just gave it to me when I was a kid…”

“This is utterly absurd,” Regulus huffed. “Do you have any idea how valuable this is? How rare this is?”

“I s’pose… I mean, I’ve never really thought about it like that…”

“Well, maybe you should have!” Regulus said, growing frustrated. “Magical artefacts like this - family heirlooms like this - ought to be treated with the respect they deserve!”

“Er, sorry?”

“So you should be!”

Regulus was aware that he was being slightly dramatic but his heart was pounding and he was clutching at the cloak like it had come from Merlin himself - heavens, maybe it had - because Potter didn’t understand. How could he stand there, so blasé, about such a precious thing?

There had been just a few short years in Regulus’s life where he thought that he might get to inherit something as precious as Potter’s invisibility cloak. When he had been a child, when he had just been the spare, Mother had made it very clear that everything would pass to Sirius. It had been frustrating, knowing that Sirius wouldn’t care for any of it properly and would no doubt let it all fester and mould in that big old house, but Regulus had accepted it.

And then Sirius had left. And Regulus had assumed the role of heir and all the responsibilities that came with that role, including the safekeeping of the Black treasures. The tapestry, of course, had long been their crowning glory. A perfect record of their ancestors, stretching back for centuries. He had even entertained fancies that he might one day discover a way to restore the names of those who had been removed - not just Sirius, and Andromeda, and Alphard, but the others too, the faceless, nameless ones, the ones who had been forgotten to the annals of time.

But now… now he was left with nothing again. The house would pass to Aunt Lucretia if she and Uncle Ignatius outlived Mother. Then back to Grandfather Arcturus, and then - Regulus could see the shimmering lines of the family tree in his mind as clearly as if they were displayed in front of him - to Grandfather Pollux, to Cygnus and Druella, and then, horrifyingly, to Bellatrix and Rodolphus and any children they might bear.

What a mess he had made of things.

They took the cloak. Regulus was tempted to refuse Potter’s offer of help on principle but his joint curiosity about Andromeda and getting to handle a rare magical artefact was too overpowering. He couldn’t understand how Potter could so easily hand over such a thing but felt reluctantly grateful nonetheless.

Sirius promised Lupin, over and over, that they would merely step outside the flat, both concealed beneath the cloak, and apparate directly to the park. Lupin reluctantly let them leave and Regulus slunk past him, careful not to touch the werewolf.

The invisibility cloak was quite large and would have easily concealed Regulus if he had been the only one wearing it, but Sirius insisted that he needed to go beneath it too. He claimed that he didn’t want to look as though he was talking to himself. 

So they huddled beneath it together. Sirius had his arm around Regulus’s shoulder again, crouching slightly to make sure the cloak concealed his hideous boots. They stepped out of the flat, and Sirius paused. 

“Fancy a little adventure?” he asked.

“What?”

“Seems like a wasted opportunity to just apparate. Have you never wanted to explore muggle London?”

Regulus hadn’t, but Sirius didn’t seem to care. 

They walked down an echoing stairwell - Regulus reminded Sirius to cast a silencing charm on their feet and oh, how he missed his own wand - and slipped out of a heavy wooden door, out onto a busy street.

Regulus froze. The November sun was shining unexpectedly brightly, reflecting off shop windows and muggle cars, so warm that he could feel it through the fabric of the cloak. He had to resist the urge to throw the cloak off and lift his face to the sun; Sirius squeezed his shoulder and they stepped out into the street.

He didn’t like it. There were too many people and too many noises. He clutched Sirius’s t-shirt with both hands and huddled closer to him, every unexpected sound making him flinch. This was a terrible idea, the worst idea. They were too exposed. All it would take was a strong gust of wind, or bumping into something or some one , for the cloak to snag on a tree branch, and they would be revealed to the whole of London.

Anyone could be there, watching. He didn’t recognise any Death Eaters but who was to say that they hadn’t been Polyjuiced? He should have been Polyjuiced. Who was to say that the Death Eaters hadn’t discovered their own source of rare, powerful, invisibility cloaks?

They reached the end of the street and Sirius pulled him into a narrow alleyway, out of the glare of the sun and the muggles.

“Hey,” he murmured, squeezing Regulus’s shoulder again. “You okay?”

Regulus nodded automatically.

“Reg. Talk to me.”

“I don’t like it,” he whispered. “We shouldn’t be here. It’s… it’s too dangerous.”

“It’s not… well, only a little bit. But we’ve got the cloak, Reg, no one can see us. Not even Dumbledore can see through this old thing so You-Know-Who and his minions have got no chance, yeah?”

Regulus didn’t say anything. He pulled away from Sirius and worried at the hem of his jumper - Sirius’s jumper, or Lupin’s jumper, or whomever the damned thing belonged to - thinking, reasoning with himself.

“What if someone does see us?” he said. “What if… what if something goes wrong? If any of them see me, with you… don’t you understand, Sirius? Don’t you understand what they’ll do?”

Sirius looked grim, his mouth set in a hard line. “Trust me, I know. Look, I should’ve…” he sighed, ran a hand through his hair. The cloak rustled and Regulus shuffled closer to him, holding the cloak firmly around them both. “I should’ve known you wouldn’t… alright. How about we just apparate from here, yeah?”

“I don’t know,” he whispered. “I don’t… what if she doesn’t want to see me? What if she’s a trap, what if she’s told the Aurors she knows where I am? What if she’s told Bella ?”

“Reg, listen. Romy’s the last person who’d dob you in to bloody Bellatrix. You’re panicking. Calm down.”

Regulus knew that he was panicking but being aware of the fact didn’t tend to do much to stop it.

“D’you want to go back home instead?” asked Sirius.

Regulus nodded. He was trembling all over.

“Alright. That’s alright. We’ll just apparate back to the flat, okay? Hold on.”

He felt like a child and he hated it but he let Sirius side-along him the short distance back down the street to the steps outside the flat. They paused, and Sirius let Regulus regain some semblance of composure before they went back inside to face Lupin.

It was here, as Regulus looked across the street and counted the number of people he could see to try and distract his mind from its panic, that he saw him. Mulciber. Wearing what looked like half his old school uniform and a garish purple jacket, lurking suspiciously and doing a terrible job of blending in with the muggles around him.

Regulus gripped Sirius’s arm so tightly that he almost squeezed it right off. 

“Reg!” he complained, trying to prise Regulus’s bony fingers off his flesh.

“They’re here,” Regulus whispered, his voice cracking. “They’ve come for me. They know I’m here.”

Sirius drew his wand in an instant, his expression deadly serious. “Who?”

“Mulciber. Maybe others, I don’t know!”

Regulus’s eyes darted up and down the street as he tried to see if any other of his former comrades happened to be lurking, searching for him, waiting to capture him and take him to the Dark Lord.

“Alright, get inside,” said Sirius. “He won’t be able to get in the building, don’t worry. Come on.”

They took the stairs two at a time and Regulus was out of breath by the time they reached the flat door, his heart pounding in his head. He couldn’t believe how stupid they had been, he couldn’t believe he had let Sirius lead him into this ridiculousness, couldn’t believe he had almost let Sirius get him killed. 

Sirius whipped the cloak off and clutched Regulus’s shoulders. “Don’t tell Moony what happened,” he whispered. “We’ll just say you changed your mind, alright?”

Regulus nodded and couldn’t imagine willingly telling Lupin anything, anyway. As soon as Sirius had unlocked the door he darted into his bedroom and curled up in the corner, his knees drawn up and head bowed, shaking all over. 

He didn’t know what to do. He didn’t know what the fuck to do.

And then his arm started burning.

He jerked his sleeve up and stared at his forearm, watching in horror as the lines of the hideous Dark Mark slowly began to darken. The skull was vibrating and the snake was twisting and turning, coiling and uncoiling, its tongue flicking towards Regulus’s wrist.

“Sirius!” he cried out.

Sirius was there in seconds, bursting through the door, Lupin just behind him.

“What is it?”

Regulus could only hold his arm out desperately, tears pricking at his eyes.

Sirius swore and bounded across the room. He knelt in front of his brother, eyes wide in horror and mouth agape as he stared at the blackened Dark Mark.

“Does it hurt?” he asked.

“Not… not yet.”

The burn was more of an itch, at first. But Regulus knew that the longer he ignored it, the greater the pain would intensify. He had once left it for fifteen minutes: the Mark had burned while he was bathing and he had thought it would be inappropriate to attend the Dark Lord half-dressed with sopping wet hair. He had been wrong. It had been far more inappropriate to make the Dark Lord wait.

“What if Mulciber saw me?” Regulus whispered. “What if— what if the Dark Lord knows? What if he knows where I am? What if he knows what I’ve done?”

“It’s alright,” Sirius whispered back, though his voice, too, was trembling. “There’s no way he saw you. We were under the cloak the whole time, remember? Mulciber’s an idiot. He can’t see through invisibility cloaks. It’s just a coincidence.”

Lupin crept over and took a good look at the brand on Regulus’s arm. He felt embarrassed, ashamed. Horrified that he was a pitiable sight even to a werewolf, but he didn’t hide the Mark away. What was the point in hiding it, when his end was now so near?

“I don’t know what to do,” he said, his throat choked.

The pale skin around his Mark began to redden and Regulus tried to resist touching it, clutching Sirius’s hand to prevent himself from scratching at the burn. 

“You know what I would suggest,” Lupin said softly.

Regulus stared glumly at the carpet.

“Why don’t we see if we can stop this thing from hurting first, yeah? Then we can think about what to do,” said Sirius.

Regulus knew that it was impossible to relieve the symptoms of the Dark Mark - he had tried every solution he could think of in the terrible pain-filled haze that had marked the days after he had received it - but he allowed Sirius to summon herbs and ointments, salves and balms, allowed him to apply them with his wand and see for himself that nothing could stop the Dark Mark’s call.

“Alright,” said Sirius, brushing a shaking hand through his hair. “Muggle stuff? Drink this.”

He dropped a couple of white tablets into a glass of water. It fizzed and Regulus was sceptical but drank it anyway. A voice in his head that sounded oddly like Professor Slughorn told him that he oughtn’t to mix unknown medicines with unknown magic, but he couldn’t bring himself to worry about that when there were so many other worries clamouring for attention in his head. So what if this muggle medicine reacted badly with the Dark Lord’s magic? So what if it killed him? He was dead anyway.

And then he realised, as his arm was angry red and burning like hell and shaking uncontrollably, that he had nothing left to lose. What could Dumbledore possibly do to him that hadn’t been done already? So what if he threw him into an Azkaban cell? He deserved it. So what if he killed him on the spot? He deserved that, too.

“Alright,” he said, trying to level out his quavering voice. “Tell him— tell Dumbledore. I’m ready.”

Lupin and Sirius stared at him in surprise, frozen for a moment, before Sirius sprung to his feet.

“Right. Get up!” he said, frantically. “We’ll apparate to Hogwarts - we’ll use the cloak. Now, come on!” 

“Sirius, stop,” said Lupin, laying a hand on Sirius’s shoulder. “We can’t apparate into the castle, you know that. It’ll be quicker if Dumbledore comes to us - I’ll send a patronus.”

Sirius nodded and crouched back down beside Regulus, blinking as he watched Lupin rush out of the room. Regulus was shaking, terrified despite his recent convictions, and clutched the warm locket around his neck. It felt like it was pulsing, matching his own racing heartbeat.

“Reg,” Sirius sighed, and Regulus was unnerved to see his brother’s bright grey eyes glossy and tear-filled.

Sirius pulled him into a hug, his strong arms enveloping Regulus’s smaller, slighter frame. He squeezed tightly and Regulus, hesitatingly, returned the embrace with his one arm that wasn’t on fire.

“We’ll fix this,” Sirius promised.

Regulus could only nod, his voice choked, his face buried in his brother’s shoulder. Sirius sniffed and took in a great shuddering breath.

“I’m so proud of you, Reg,” he said, stroking the back of his head. “I promise I’ll never leave you behind again.”