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The seal has been fading for years.
Isshin feels it within his own chest. Feels the slow drain of power without Masaki’s soul to anchor it.
He has to tell Ichigo. But they have a few more years. Ichigo’s happy right now. Young. He gets into plenty of fights, but what Shiba doesn’t, and he’s doing well in school. There’s no reason to upend his world yet. The seal is failing, but by the time it fails entirely, Ichigo will be graduating and heading to university. He’ll tell him…in his third year, maybe, depending on how things go.
He’s testing a late-night patient for mono when he feels the seal freeze, crackling with ice before it shatters. He clutches a hand to his chest. Ow. What the hell was that?
He looks out the clinic window and sees a shinigami for the first time in twenty years.
And the shinigami is his son.
His son, holding an absurdly large asauchi and springing at a Hollow, destroying it easily. He goes to someone dressed in white, slumped by the streetlight.
Goes back out, does his job.
Texts Kisuke the seal is gone.
Kisuke texts him back the next morning. Guess who came looking for a gigai today?
Isshin calls him, because Kisuke will draw it out otherwise. “Who is it? A shinigami?”
“Well, former shinigami,” Kisuke drawls. “Your son accidentally ‘borrowed’ her entire store of reiryoku. Left her bone dry. Kuchiki Rukia-san.”
He groans. “A Kuchiki?”
“Adopted Kuchiki,” Kisuke says. “Based on what she asked me about, she’s going to have your son perform her duties for her while she’s indisposed.”
“What about the Hollow?”
Kisuke hums. “His reiatsu feels purely shinigami for now.”
Maybe…they don’t have to talk immediately, then. Any Kuchiki can handle teaching Ichigo swordplay. He’ll learn, protect Karakura, and when he’s an adult…
Isshin throws himself into acting normal. He waits to feel Ichigo’s (and Kuchiki’s) reiatsu come home before he goes to bed. He makes sure he treats Ichigo the same way as always, checking his reaction time. He seems fine. Annoyed, but fine.
Ichigo gets more and more antsy, though, and one night Isshin feels captain class reiatsu what the fuck flaring, Ichigo’s pushing back.
Then it fades all at once.
He calls Kisuke, who already knows, already has him, says Byakuya burned out the borrowed power but he’s alive. Byakuya. Of course.
Kisuke tells him Ichigo wants to activate his own powers.
“It’s more than likely going to awaken his Hollow,” he says with a sigh, leaning on the railing at the back of his shop. “The best way to make him a shinigami is to cause the Encroachment under…controlled circumstances.”
“You’re talking about killing him.”
“Yes,” Kisuke says, deliberately light. “I can modify his body to allow it to continue with basic functions in his spirit’s absence, but effectively, he’ll become a soul. He should continue growing and physically be identical to a human, if he doesn’t fully Hollowfy. If he does…”
“If he does, I’ll lose my son.”
“And we’ll lose our best chance against Aizen.” Kisuke sighs. “But there’s no Quincies left to train him, other than Ryuuken-san and Uryuu-kun. Even if he knew what Masaki was, we wouldn’t be able to teach him anything. Awakening his shinigami side is our best option. At worst, hopefully, he’ll become something like the Visored.”
“It’s his choice.” Isshin knows what his son will choose. Ichigo’s been moping, dragging his feet, missing his shinigami. The girls haven’t noticed yet, but they will.
When Ichigo disappears for a few days, Isshin paces a hole into the floor and wonders why he didn’t say anything before Ichigo left. If he Hollowfies now…
He comes home grinning and full of an absolutely bullshit story that Isshin pretends to buy. Sends him up to sleep and thinks thank God.
Tells himself he’s going to tell Ichigo the day he goes to Soul Society. Ichigo leaves bright and early and Isshin comes down with a protection charm for him.
Chickens out.
He’s about to go take on the Seireitei. With Yoruichi, granted, which is the only reason he isn’t threatening Urahara to lock them all up. He doesn’t need Isshin dropping a bomb on him right now.
Besides, Ichigo has his mother’s name, his mother’s hair. Nobody will look at him and think Shiba. And he was the last high-ranked Shiba in the Gotei 13, after Kaien, rest his soul. Nobody left who’s close enough, and what are the odds Ichigo will run into the non-Gotei Shiba?
He comes back with changed reiatsu. Quiet, thoughtful. More shinigami arrive in town.
(Seeing Toshiro and Matsumoto hits like a stab to the heart and he thanks his lucky stars Ichigo never brings them home for dinner.)
He meets Kuchiki Rukia and puts on a show of wailing for the tragic story she tells him. She’s certainly an excellent liar. Isshin wouldn’t have seen through her if he didn’t know who she was.
He doesn’t let her sleep in Ichigo’s room, though. Shinigami or not, Ichigo is a teenage boy, and Isshin remembers his…inadvisable life decisions at his age with a wince. Definitely not sharing. They cram her into the twins’ room. Urahara slips him a charm to conceal his reiatsu, not that he thinks anyone can sense anything as long as he’s near his son.
Ichigo leaks reiatsu like a punctured tire. His control is abysmal. He’s strong, captain-class (already, not even a shinigami six months), and when he brings it up, Yoruichi laughs and tells him Ichigo not only got shikai but bankai in Soul Society.
“Bankai? That takes—“
“They used an old shortcut of mine,” Kisuke says, a smile playing on his lips. “He challenged Captain Kuchiki. He would have been killed without bankai.”
“I had to carry his idiot ass out of there with flash-step,” Yoruichi snorts. “He cut it close, but he got it. I’m more worried about the Hollow mask that kept showing up on him. He won’t say what happened against Byakuya, but I overheard him talking to his sister. Saying there’s a Hollow inside Ichigo.”
“Maybe he just felt the reiatsu,” Kisuke suggests. “You said it’s fairly Hollow in bankai?”
“Yes— which makes no sense, incidentally. His sword spirit isn’t Hollow at all, but when he’s in bankai his reiatsu shifts noticeably. I doubt that’s it, though. Byakuya said ‘it’ had admirable strength and that Ichigo intervened between them before it could finish him off.”
“So it tried to consume him,” Kisuke says, brow furrowing. “I’ll tell Shinji and the Visored. Hopefully they’ll make their own overtures. We don’t speak often, but they’re a tightly knit group. Finding someone else like them…”
“I can’t believe Aizen finally revealed himself,” Isshin says, shaking his head. “Ichigo does have a talent for shaking things up.”
“It’s the Shiba genes,” Yoruichi says dryly. “Him, Gin, and Tousen. The shinigami are preparing for war, but that shikai of his…I’ve never seen one so strong. Perfect hypnosis. And almost everyone has seen his release. Ichigo hasn’t.”
“If he wasn’t our best hope before, he is now,” Kisuke agrees. “…I hoped he would have longer.”
More of a childhood.
“We’ll deal with Aizen and he can go back to his regular life,” Isshin says firmly. “Let’s start planning. Now that Aizen’s revealed himself, I think you ought to contact Seireitei, Kisuke—“
They plan. They talk.
Inoue Orihime goes missing.
Ichigo leaves the house and doesn’t come back.
When Kisuke comes to his door, he smiles an apology with his eyes hidden, and Isshin knows where his son is.
He helps with the preparations. Has some awkward conversations and the singular experience of his former Third Seat using him as bankai training, flying after him in betrayed fury. He releases Engetsu in turn and they fight it out, and at the end of it all his two former subordinates drink with him at Kisuke’s and he compliments Toshiro on what a splendid captain he’s become, his bankai, his control. Toshiro blushes ears to throat and pretends he’s unaffected.
It all comes to a head when he kicks Ichigo off a building in a false Karakura Town.
He expects his son to be venom-spitting furious, and at first he is, thrashing furiously as Isshin shushes him. But then he gets out and says he just wanted to breathe and stops even trying to yell.
I can’t figure out how to ask, he says, and Isshin sees overlaid the little boy who cried at karate practice, the teenage delinquent who came home with split knuckles and a black eye or cut lip or swollen cheek, and Ichigo as he is, the youngest-ever to master bankai, Ichigo who took on a Captain and won, Ichigo who invaded Soul Society and Hueco Mundo and lived.
His boy grew up when he wasn’t there.
I can’t figure out how to ask without tracking mud into your heart, so…I’ll wait until you’re ready to tell me.
He calls himself a cursed coward. He wants Ichigo to scream at him, punch him, draw his sword. He wants Ichigo to demand answers and Ichigo just leaves it. Sees Isshin and Engetsu, his captain’s haori over one shoulder, and leaves the matter there.
Ichigo’s always been expressive, and seeing the hurt in his eyes as he tells Isshin he’ll wait… This is why he didn’t want to tell his boy.
But he should have. He should have been braver. Should have come out into the light before he was forced to. He’s not his son. His son is bright and courageous and stands up for what he believes in. He doesn’t flinch from what needs doing. Isshin flinched for nearly two decades, and now…
He’s lost something. Something in how Ichigo looks at him, those deep brown eyes hiding his betrayed heart. Setting his own feelings aside on behalf of someone else. He’s so very like his mother that way.
They fight. They fail. Aizen goes to Soul Society.
They go too, and Isshin tells Ichigo of the Final Getsugatenshou.
He would do it himself if he could. But his reiryoku is maybe a tenth of Ichigo’s (he’s so proud, sixteen and eclipsing Captain-class shinigami, eclipsing his four-hundred-year growth), and nowhere near Aizen’s impossible strength. Him using this technique might tickle Aizen a little, at best. He’s not sure even Ichigo has the strength for it to kill Aizen.
This was a backup to a backup to a backup. It was never Plan A. He never wanted Ichigo to get hurt.
But this is what it’s come to, so he sits and freezes the current and hopes until he falls unconscious from the strain.
He misses Ichigo’s big moment. He misses Urahara sealing Aizen.
Sits down and trims his son’s shaggy hair while he’s unconscious, feeling wildly out of his depth. His own hasn’t grown at all— he’s a soul, not alive, and seeing Ichigo’s hair grow reassures him that his son is still alive in the mortal sense. Souls take decades and centuries to change appearance. Ichigo took three months.
When Ichigo is as-fine-as-he’ll-be, when the girls have been reassured and Ichigo’s hugged them and apologized profusely for vanishing, Isshin goes back to Kisuke’s.
Meets the Visored, who greet him with Kisuke roped you into his shit too, huh? and laugh at Kisuke’s faux-offended squawking and get blackout drunk with him, celebrating Aizen’s defeat.
Mourning Ichigo’s loss.
Isshin has lived with the other half of himself sealed away. He knows the hurt of losing the spirit world intimately.
He learned to live with it.
He hopes Ichigo will too.
Ichigo doesn’t.
Oh, he puts on a good show. Gets it from Isshin. He goes right back to school, works his ass off, gets his class rank out of the trash and where it should have been all along. He gets a part-time job. Normal teenage things.
Karin starts seeing spirits. Isshin insists on walking her home past Kisuke’s shop when it becomes clear she doesn’t share her brother’s attitude toward ghosts, and pretends he has no idea what she’s talking about when she spots it. She goes back on her own, of course, and Kisuke gives her an entire anti-ghost arsenal that’s mostly untrained-child appropriate. Ichigo figures it out, he can tell from how his face changes when he looks at Karin trying to discreetly shoo a ghost away. They don’t talk about it.
Ichigo stops screaming himself awake, but he doesn’t stop having nightmares. Isshin leaves a sleep aid on his desk and it sits there untouched. He can hide his reactions, but not the toll it’s taking on him. He sees how Ichigo reaches for a sword that’s no longer there and never will be again. Sees how he hunches over and makes himself smaller, a wounded soldier. Sees the lights on at three am and hears Ichigo reading Shakespeare quietly to Kon instead of sleeping.
He says to Kisuke, could you help him? and Kisuke responds it’s his choice but starts working on a plan anyway. Isshin asks Engetsu about the Final Getsugatenshou, how it works, and the spirit explains to him once he’s sure Isshin isn’t planning to use it himself. Isshin explains to Kisuke in turn, and Kisuke vanishes into his lab to perform hopefully-ethical mad science.
Then Ukitake comes and sits them both down and tells them about the first substitute shinigami. How they’re worried he might go after Ichigo.
What the badge they gave him does.
“Hmmm. Well, that is a problem,” Kisuke acknowledges at the end of the story. “Surveillance on a known loose cannon, with a strong sense of justice. A Shiba, no less— don’t tell me you didn’t know back then, Captain Ukitake, he looks like Shiba Kaien’s second coming. What led Seireitei to this decision?”
“Primarily his reiatsu control— or lack thereof,” Ukitake says, taking a calm sip of his tea. “As I’m sure you noticed, Kurosaki-kun’s reiatsu is difficult for his human body to contain. There’s a siphon in the badge that allowed us to drain the excess— and incidentally power most of Seireitei,” he adds offhandedly. “Without it, I doubt he could exist very long the way he is.”
A soul in a living body, Ukitake means. A dead boy possessing his corpse. A soul so strong he could take on any captain and win, the Head Captain included.
Could have, anyway. Before.
“I won’t sit here and assure you it was entirely altruistic,” Ukitake continues. “There were those who wanted to see Kurosaki Ichigo’s sword locked away for good. Who wanted his chain cut again, or at the very least wanted him imprisoned. This was…a compromise.”
Isshin wants names. Wants to unleash Engetsu on every shinigami and noble who argued that his son was a threat. If Ichigo threatens anyone, it’s because they were doing something wrong. His sense of justice won’t let him sit by.
The remnants of his good sense tell him Ukitake is leaving the names out for good reason. Isshin would fight them, and so would Urahara, if they tried to hurt Ichigo. Soul Society doesn’t need more upheaval.
“The shinigami stationed in the next town over sighted him and reported it,” Ukitake says. “The first substitute shinigami, lost to us under unknown circumstances. We did send a search party, and concluded from the remaining reiatsu in the air that he’d been killed, downing the Hollow he was fighting before his death. Evidently, we were wrong.”
“So what do you propose?” Kisuke asks lazily.
“Seireitei will wait,” Ukitake answers. “If he becomes aware of it, we’ll bear witness to his choice. If he doesn’t…well, then the Soul King willing, he’ll live out the rest of his mortal lifespan in peace.”
“He’s not happy in peace,” Isshin says with a sigh. “He misses having something to fight for.”
“I believe I have a way for him to take up his sword again,” Kisuke says, looking directly at Ukitake. “If you want to begin paying your debt to Kurosaki Ichigo, get me an audience with the Captains and Lieutenants. All of them.”
Ukitake inclines his head and takes his leave.
Are you sure? Kisuke asks once, twice, over and over, and Isshin thinks of sleepless nights and forced cheer and how Ichigo doesn’t talk to any of his spirit-sensitive friends anymore, not even Sado, and says yes, stop asking me.
Rukia winds up being the one to pierce through Ichigo with the sword. They get there just in time to see Kugo Ginjo take his badge. To see Ichigo’s reaction. He crumbles, all his pride and stubbornness gone in a flood of tears that’s been building since the day a Hollow took Masaki.
He passes the sword to Rukia, says softly you can reach him, and bless her for being a Kuchiki about it and not hesitating to shout Ichigo back into action. He plays his part perfectly, pushing down the voice telling him he fucked up he fucked up that sounds a lot like Toshiro.
The secret’s out, now, and Ichigo is back to himself. He defeats Ginjo, chooses Soul Society over the first Substitute Shinigami. His shinigami friends kidnap him for sake, and Ichigo either doesn’t drink any or has an iron constitution, because he doesn’t need Isshin’s anti-hangover kido the next day.
For a couple of months, everything is fine.
Everything is fine until Ichigo vanishes, until Kisuke says Seireitei’s being attacked and he’s gone to help, until Ukitake contacts him grim-faced and says the Head Captain is dead. Until Kyouraku comes to his door with a drawn expression and tells him his son’s bankai is broken. Until Shinji calls to tell him Ichigo is with Squad Zero.
Until Squad Zero kicks Ichigo out, and instead of the homing kido dropping him at home, it puts him outside his boss’s place. Because he trusts his boss more than Isshin. He has to go pick Ichigo up, like when he was still small. Goes in shinigami form to avoid awkward questions (coward, says Engetsu, and Isshin says nothing in return).
Finally telling Ichigo the full story feels like peeling a scab off a half-healed wound. Sticky edges separating from shiny pink skin, crusted red catching under fingernails, fresh blood welling where the scab was torn away too soon. Masaki. White. Ryuuken. Kisuke. How he lost his powers. How the seal faded every day that passed without Masaki.
The night Ichigo became a shinigami and how he’d felt the seal snap under the pressure of ice and snow.
Ichigo goes back. Isshin doesn’t say he’s sorry, even though he is. Ichigo doesn’t say he forgives him. Ichigo returns to Squad Zero with his face set, finally knowing who and what he is, and leaves Isshin behind.
He sits Karin and Yuzu down and claws the wound open all over again. Karin calls him an idiot and Yuzu hugs him. One of them definitely got the Shiba genes.
He tells his daughters he loves them, and to take care of each other, and finds Ryuuken.
Finds the doctor slumped over his notes after what looks like an all-night research bender.
He brings water and food and waits until Ryuuken wakes, needles him until he says Uryuu is gone.
Dead?
Yhwach’s.
They have a drink together. Just one. To love and how fucking useless it is, in the end. Ryuuken opened his heart, married for love, and Yhwach took it away. He tried to raise his son to be strong, to ignore his Quincy heritage, and now his son is Yhwach’s heir.
Isshin isn’t doing much better. He gave his life up for Masaki and Masaki is gone. Ichigo is a shinigami and a Hollow and a Quincy, a hybrid so strong Soul Society looks to him to solve invasions single-handed. Ichigo chose his own path while Isshin was paralyzed with indecision. Some father.
Ryuuken knocks his drink back and says, “We can still stop this.”
Takes out his notes from the autopsy he did on his own wife (crazy bastard).
Talks to Isshin about Auswählen, about silver in a Quincy’s heart.
Isshin says can you fight him? and he’s not talking about Yhwach. Ryuuken’s mouth goes tight, and he nods, once, and no more is said. Nothing needs to be.
They get there and it’s all moot. Uryuu is fighting by Ichigo’s side and Ichigo is resplendent in bankai, White’s horn and his own estigma and his shihakusho all around him, blut vene sparking. Allies again. Isshin has no idea, until later, if it was planned or if Ichigo stabbed the sense back into him, but he sees the relief on Ryuuken’s face before he can hide it.
Uryuu fires Ryuuken’s arrow.
Yhwach falls.
Ichigo kills him, his son, more powerful than anyone else in the worlds, his son who introduces Isshin to Grimmjow and Nelliel the arrancar, Kuchiki Rukia and Abarai Renji the shinigami, Yukio and Riruka the Fullbringers. Sado, Inoue, and Ishida Uryuu.
Ichigo who goes home and sinks into his human body and goes to school the next morning. And the next and the next.
The Gotei don’t bother stationing a shinigami in town anymore. (He asks Kyouraku directly, what will you do with him? and Kyouraku smiles and says let him live a full life. We’ll be here when he’s ready. )
Ichigo goes to college, then gets a job translating. Gets a real, human life, the life Isshin wanted for him.
His son is a far better man than he is, but that’s how it should be. The young should outshine the old. Ichigo will be a wonderful father.
Sometimes you can’t help but raise a good kid, just because you get lucky. Isshin is very, very lucky in his three children.