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Katsuki was wandering the mall with Kirishima and Kaminari on a Saturday in mid-December of their first year. The condiment twins had dragged him here to do some Christmas shopping. Feeling impatient and wanting to go back to the dorms, he threw his head back and sighed loudly.
While not paying attention to where he was going, a little girl bumped into him. He looked around for the source of the bump, but then he felt a sudden tingling sensation.
"Oh no! I'm so sorry!" a woman's voice cried. "She doesn't have control over her quirk yet! It'll wear off between 24 and 48 hours from now and your friend will be back to normal, I promise," she explained to Kirishima and Kaminari.
Katsuki, on the other hand, found himself swimming in clothes that were much too big for him and standing in a mall he didn't remember going to.
He saw two teenage boys standing nearby, looking at him slack-jawed.
"What are you looking at?" he sneered. He may only be 7, but Bakugou Katsuki doesn't let anybody disrespect him. Even that stupid idiot Deku finally stopped following him around.
The shark-toothed one with heavily gelled red hair snapped himself out of his trance first and looked back at the woman and her young daughter.
"Sorry, ma'am, but we'll need your contact information in case something goes wrong with the quirk." The boy took an ID card out of his pocket. "We're first-year students in the hero course at UA."
"Oh dear. I hope Yuki's not in trouble-"
Katsuki tuned the woman out and directed his attention at the blond boy.
"Hero students at UA, hah? What's your quirk then? Where am I and why are my clothes too frickin' big?"
Blondie finally wiped that idiotic look off his face and grinned. He held up his hand and electricity danced around his hand and forearm.
"I can generate electricity. Like this!"
"Oh. So you're Pikachu then." Katsuki smirked.
The teen dropped his head and sighed. "You actually think I'm pretty useful and team up with me in class exercises all the time. You're a hero student too, Kacchan! Well, normally you are. You're in my and Kirishima's class and you've got your UA ID on you as well. We were just Christmas shopping when that little girl accidentally quirked you into a... Wait, how old are you?"
"Not that it's any of your business, but I'm 7," Katsuki haughtily declared. "And don't call me that! Bakugou or Katsuki is fine."
Katsuki crossed his arms and pouted. He was too old for that nickname! Especially if he's not actually 7 now. Only dumb Deku still called him that. Katsuki had long since given up on trying to get Deku to stop. At least Katsuki called him Deku in return.
"If you know me, what's my quirk? And how does it work?"
"Explosion and you sweat a nitroglycerin-like substance from your palms. The name is Kaminari, by the way," he finished with a smile and thumbs up.
Katsuki scowled even more, but he relented. He reached into his pocket and pulled out a UA student ID card with a picture of himself, but older, on it. "Alright, I believe you and Shark Face."
Said redhead must have finished talking to the girl and her mom because he'd turned back to Katsuki and Kaminari.
"So, Bakugou! We were going to head back to the UA dorms, but I guess we should call your parents instead, huh?"
Go back to UA?! Where he's a student like he always knew he would be?! And they lived in DORMS?! That must be a new feature; UA didn't have students living on campus the last time he looked up the school.
No way did Katsuki want the hag butting in when this amazing opportunity had presented itself.
"No! Let's just go back and tell the teacher or whatever. The lady said it would wear off soon anyway."
Kirishima thought for a moment and said, "You know what, Kaminari? He'd probably be safer at school. Imagine if the League caught wind of this?"
Katsuki didn't understand the "league" comment but Kaminari agreed with Kirishima, which meant Katsuki was going to UA without much fuss.
"Before we go anywhere, though, Bakugou isn't going to be able to make the trip back to UA with these giant shoes and clothes on. Since we're in the mall already, let's get him some stuff that fits," Kaminari pointed out.
Katsuki was about to open his mouth to protest because he wanted to see UA as soon as possible, but he had to admit that the way he was dressed right now was highly impractical. He was getting nowhere fast in these clown shoes.
"Fine." He looked around and pointed out, "There's a department store over there the old lady has taken me to before. Let's get this over with."
They quickly bought him pyjamas (All Might ones, of course), two outfits, slippers, shoes, and a jacket for the December weather using the credit card Katsuki's parents had given him for emergencies. Katsuki changed into one of his new size-appropriate outfits at the store and packed his teenage clothes into one of his shopping bags. As they finally started on their way back to UA, Kirishima called the school to relay what happened.
"Oh, I just remembered, you still know Midoriya at this age, don't you, Bakugou? You two can have a little reunion!" Kaminari chuckled.
"DEKU GOES TO UA?! HE DOESN'T EVEN HAVE A QUIRK!!"
During the trip back to campus, Katsuki was consumed with thoughts about Deku. Had he been hiding his quirk from Katsuki? Did it just come in super late? What about what Deku's doctor had said about his toe joint? What is Deku's quirk? Is it better than his? He really had been looking down on Katsuki all this time!
Katsuki was seething. He was going to get to the bottom of this!
Once they'd reached Class 1-A's dorm building, Katsuki was ready to rampage. If only he knew where he was going!
However, his rampage would have to wait. A man with black hair, tired eyes, and stubble was waiting for him, Sharky, and Sparky on the porch.
"Aizawa-sensei!" Kirishima called as they approached.
Aizawa looked Katsuki up and down and sighed. "Bakugou, I'm Aizawa Shouta, your teacher here at UA. Kirishima and Kaminari explained what happened and I've contacted your parents. They agreed for you to remain here while the quirk is in effect."
Thank god the old hag was being halfway sensible.
Aizawa continued, "Since this is a temporary situation, I trust you'll be on your best behaviour. If you aren't, I will have your parents pick you up and take you home until the quirk has worn off. Understood?"
"... Yes, sensei," Katsuki said begrudgingly.
"Good. In that case, I'll leave you to it," Aizawa said with a nod and left.
Wanting to stay at UA, Katsuki reeled himself in a bit. He would still get his answers from stupid Deku, though.
They entered the building and changed out of their shoes and into slippers. Katsuki felt his heart rate spike; he could confront Deku now. He heard chattering and stomped off in that direction, coming across a spacious common room. Immediately a dozen faces he'd never seen before, and one he couldn't stop seeing (no matter how hard he tried) turned to look at him.
"OH MY GOD HE'S SO CUUUUUUUTTTEEEE!!!" a pink girl with horns and raccoon eyes screeched and ran towards him.
He lifted his right palm and let off a few warning sparks. "Back off, Pinky!"
Seeing the sparks, she slowed down her approach.
"Oh, you said my hero name! Do you remember me, Bakugou?!"
"What? No! You're pink! What else am I supposed to call you?"
"Haha, same old Blasty! Guess he hasn't changed that much since he was a kid, huh?" she laughed.
Done with this conversation, he zeroed in on Deku's anxious face.
"Deku!"
"Heh heh, hey, Kacchan." Deku chuckled nervously and stroked the back of his neck with one hand while he walked closer to Katsuki.
Katsuki felt a bit taken aback. He really had been quirked into a younger body!
After having been taller than Deku all their lives, Deku now towered over him, though he was by no means the tallest in the class from what Katsuki could see. His face was basically the same, but his jaw was more defined and his cheeks were less chubby. Green hair was still a curly mop atop his head and those vibrant viridian eyes were huge and sparkling as always.
The biggest change was Deku's body. Katsuki could see he was no longer the scrawny nerd he knew. His shoulders and chest had broadened and the way Deku's arm had come up to scratch his neck showed off a well-developed bicep underneath his long-sleeved shirt. Also, his hands were scarred... How did he get those?
Feeling a blush coming on, but refusing to let it show, he shouted, "How did you get into UA, Deku? You can't do anything!"
Deku's face hardened slightly and said, "Kacchan, let's talk about this in my room, ok?"
Izuku was disappointed in that remark. Kacchan continually challenged him now, but those comments motivated him. Little Kacchan yelling that he can't do anything is an unpleasant blast from the past. But! He had to remember, Kacchan was only 7 right now; he didn't know about everything they'd been through this year. Kacchan had grown so much as a hero!
Katsuki bristled at Deku's expression and backtalk, not liking it one bit. "Don't tell me what to do, Deku! But fine, I don't want these extras gawking at me anyway."
Katsuki loved attention, especially in the form of praise, but his curiosity and outrage trumped that right now. Besides, he had the feeling that any attention he'd receive from his supposed classmates right now would just serve to annoy him if the pink alien girl was any indication.
Deku left the common room, expecting him to follow, and while that pissed him off further, he had no choice. There was a goal here... and he didn't know where he was going.
They went to an elevator and Deku pressed the button for the second floor.
"Your room's on the fourth floor, Kacchan."
"Tch." Useful information, but he wouldn't tell Deku that.
The elevator opened onto the second floor and they approached a door that had Deku's nameplate next to it. Deku opened the door, sat down on the bed, and Katsuki felt his mouth drop open. His room was a veritable shrine to All Might!!
Deku had always had an impressive All Might merchandise collection; one of the less useless things about him. Years ago, back when they used to go to each other's homes to play, Katsuki had secretly appreciated how much of an All Might nerd Deku was, matching him in enthusiasm and All Might trivia.
He wanted to see and touch, but that's not what he was here for and they weren't friends anymore. Katsuki had made sure of that.
"Alright, Deku, spill! Do you have a quirk? What is it? Why did you hide it from me?"
Izuku noticed the awe that briefly flashed across Kacchan's face as he regarded Izuku's All Might-themed room. It warmed his heart to see that childlike zeal on his childhood friend's face again. He hadn't seen him look like that in so long.
Izuku was reminded of how before Kacchan got his quirk, he and Izuku used to play without the rest of their neighbourhood gang at each other's homes from time to time. Without the others there, Kacchan was still Kacchan, but he was a little softer. He didn't try so hard to be the top dog. He let his and Izuku's shared passion for All Might and heroes fuel their playtime.
Before Kacchan, Kirishima-kun, and Kaminari-kun had returned from the mall, Aizawa-sensei had informed them that Kacchan had been temporarily quirked back into his 7-year-old self, so Izuku was prepared for Kacchan in this form. But seeing 7-year-old Kacchan question him like this made Izuku experience deja vu for when he and Kacchan were actually 7, and for the beginning of their time at UA when he and Kacchan went head to head during that first battle training exercise. Deja vu times two.
When both of them were 7, their friendship had broken down by then and they avoided each other. At the time, Izuku didn't understand why Kacchan pulled away. Had something happened? Izuku didn't remember doing anything in particular to upset Kacchan. He tried chasing after Kacchan for a while, but he consistently blasted Izuku away and yelled at him about his quirklessness. The other kids made fun of him for it too. Izuku eventually got the message and stopped seeking out Kacchan, though it saddened him to do so. Kacchan was still amazing! Izuku held onto the increasingly futile hope that one day they could maybe be friends again.
And then the fight at Ground Beta happened. Things have been improving since then! After all, Kacchan said things would be different and they had been. It was monumental for Izuku to learn that Kacchan thought he'd been looking down on him all this time. Plus All Might mentioned that Kacchan feared his spirit, even though Izuku couldn't wrap his head around the concept of Kacchan being scared of him.
It was also important for Izuku to learn that Kacchan felt responsible for All Might's retirement because he'd been kidnapped and needed rescuing, and that he'd been carrying that burden all that time. While Izuku didn't want Kacchan to feel bad about something that wasn't his fault, knowing he did feel bad weirdly comforted Izuku. It was another example of Kacchan's good side; that he cared about people and took responsibility for his actions. That he always wanted to pull his weight and not owe people.
Now that Izuku understood a little bit more of the enigma that was Kacchan, he wanted to use that knowledge to get on the right foot with this little Kacchan, as temporary as this situation might be.
"Yes, Kacchan, I have a quirk. It's a strength quirk similar to All Might's, and it came in late. The big version of you knows all about it. Do you want to see it?"
Katsuki shuffled his feet on the ground nervously. Useless Deku had a quirk like ALL MIGHT?! He didn't know how to feel about this.
Izuku wished he had better control over Blackwhip so that he could pass it off as his sole quirk. He figured Kacchan would have less complicated feelings about that quirk.
"It's not all it's cracked up to be. I can't fully control it yet and I've broken bones using it at 100%." He lifted his hands, turned them over, and ran his fingers over the most prominent scars. "But you and All Might have been helping me train my quirk. Kacchan's been a great rival to me."
So that's where the muscles and scars came from. Katsuki relaxed a little. Deku couldn't be looking down on him if Katsuki was helping him, right? Needing help makes Deku the weak one!
"Of course you'd be useless with your quirk, stupid Deku! What's the point in being number one if I only had useless extras to compete with," he huffed.
"You're right, Kacchan. I'm doing my best to catch up to you."
Izuku smiled at the boy and clenched his fists. Izuku wanted to challenge him back and say he'd surpass him like he usually does, but that sentiment was for normal Kacchan. He shouldn't tease child Kacchan too much.
Katsuki felt another blush coming on and decided now was a good time to go to his own room and see what his teenage self had done with it. He didn't anticipate this strange future where it seemed like he'd acknowledged Deku. He figured he'd leave behind everyone he knew from kindergarten to middle school, including Deku, when he went to UA. He's not sure how to handle this confident, more grown-up Deku with his smiles, muscles, quirk, and needing his help.
Katsuki looked longingly around Deku's room. "Well, I've got better things to do than hang around here all day," he announced and turned towards the door.
"Wait, Kacchan! I've got some All Might merch you wouldn't have seen just yet. Wanna stay?" Deku offered.
Katsuki was tempted, but he couldn't handle that just yet, he needed some time alone to process everything that had happened.
"My room is probably 10 times better than yours, dummy!" he yelled and abruptly took his leave.
The door slammed behind him and Izuku smiled to himself.
"Kacchan is Kacchan."
Katsuki stomped over to the elevator, entered, and pressed the button for the fourth floor. Once there, he looked around and found the door with his own nameplate on the outside. He was still carrying his shopping bags with all his stuff from the mall in them, so he looked around for a key in the pockets of those too-big pants, found it, and let himself in.
His room was surprisingly sparse compared to Deku's with only one All Might poster on the walls. It was a damn good one, though, as it commemorated the 20th anniversary of All Might's debut. It was in a sleek black frame he suspected the hag had picked out. Apparently, his tastes had changed as he got older because the All Might overload chaos of Deku's room appealed to his current 7-year-old preferences more. Oh well.
Katsuki put everything away and flopped down on the bed. What a day!
He was a hero student at UA! But so was Deku. Big Deku. Big Deku, who needed Big Katsuki's help to manage his quirk because it was so powerful it broke his own bones... Big Katsuki, who was willing to help Deku...
Why? What happened between them?!
The Deku he knows is small, scrawny, and can't do anything! He'd finally left Katsuki alone!
Deku, who defended that kid Katsuki had made cry in the park that day. Deku, who offered his hand to Katsuki when he was fine after he fell in the river. Deku, who always said Katsuki was amazing and yet still made that face like he was the only one in on the joke. Deku, who chased after him when Katsuki pushed him away.
Katsuki just didn't understand him! Deku made Katsuki feel weak. Like he was missing something, and that is just not allowed. So no more Deku! Katsuki is supposed to be the strongest of them all! Look at his quirk! His intelligence! His talent!
Katsuki suddenly remembered something. Deku said he AND All Might were helping him.
WHAT?!?!?!?!?!
Katsuki leaped out of bed and burst out the door. He raced back down to Deku's room and pounded on his door. A startled Deku let him in.
"WHAT DO YOU MEAN ALL MIGHT IS HELPING YOU? IS HE HERE? WHERE IS HE? CAN I MEET HIM? IS HE JUST HELPING YOU? TELL ME EVERYTHING!!!"
Kacchan had grabbed hold of Izuku's shirt, as high up as he could reach, and was shaking with excitement. His red eyes were wild.
Izuku had already decided he wouldn't tell little Kacchan about OFA and his connection with All Might; that wouldn't help things between them. As much as it bothered him to not tell Kacchan everything, for reasons unknown, he reassured himself that normal Kacchan already knew everything, so Izuku wasn't technically lying or withholding.
Izuku chuckled. "Oh, All Might is a teacher here! He started this year. He helps everyone, you included, Kacchan. Unfortunately, he's away on a mission this weekend and isn't on campus right now, so I can't take you to meet him." Izuku frowned, knowing this would disappoint Kacchan, but All Might couldn't maintain his muscle form anymore and he actually was away, gathering information on OFA.
Katsuki immediately deflated, "Oh... well at least big me knows him," and then Katsuki remembered, "AND I'M ONE OF HIS STUDENTS! I'M HIS FAVOURITE, RIGHT?!"
"Yeah, you've even had tea with him!"
"SO! COOL!"
Katsuki couldn't contain his excitement anymore and started punching and kicking pretend air villains. "All Might always wins! I bet he's the best teacher here! Better than that hobo guy from before!"
"All Might is the best! It's really special being here at UA with him. But, Kacchan, Aizawa-sensei is an amazing teacher too. He's the underground hero Eraserhead, and has excellent hand-to-hand combat ability."
"All Might's still the best though."
"Haha, yeah."
Izuku couldn't stop smiling. Interacting with little Kacchan like this was like a dream come true! His bright red eyes danced with excitement while proud blond spikes swayed with every kick and punch. Izuku never thought he'd experience something like this again. It reminded him of happier times before quirks, quirklessness, and misunderstandings came between them.
After executing a perfect roundhouse kick, Katsuki regarded Deku's smiling face and thought about what he'd been pondering in his room.
"Deku... why am I helping you?"
"You said it yourself, Kacchan, what's the point in being number one if the rest of the competition doesn't measure up? I have a lot of trouble with my quirk, and you have such excellent control over yours. You're a real inspiration to me."
Izuku found it easier to talk to this younger Kacchan. It was kind of like talking to Eri-chan or Kouta-kun.
During the fight at Ground Beta, Izuku had thought that he never felt good about channeling Kacchan's potty mouth when he wanted to win more than save. But when All Might said he and Kacchan could become the ultimate heroes who save by winning and win by saving, Izuku had made his peace. Kacchan is his image of victory and that's nothing to be ashamed of. Who else shines as brightly as he does?
"I never looked down on you, you know? When I'm in a fight, I think about what you would do and it gives me strength. You always win in the end too."
This time, Katsuki couldn't hide his blush, but his bluster reflex game was strong. "Obviously, dumb Deku."
Katsuki stared at the floor. A change in subject was needed.
"What do we do for food around here, anyway?"
"Oh! We've got a fully stocked kitchen with wonderful facilities. I can take you if you want."
"Only because I'm already hungry."
Katsuki led the way out of Deku's room and toward the elevator. He let Deku press the buttons, though.
Izuku noticed.
When Deku and Katsuki reached the kitchen, they saw that dinner for everyone had already been prepared.
"Bakugou! Grab a plate and come sit with us!" Kirishima called.
"Don't tell me what to do, Weird Hair!"
Katsuki snuck a look at Deku. The conversations he and Deku had had were kind of intense. He wasn't feeling angry at Deku anymore; he was even starting to enjoy the nerd's company again... weird. Maybe he should sit with someone else.
Katsuki dismissively waved his hand in Weird Hair's direction and plated his food.
As he sat down at a table with Kirishima, Kaminari, the pink girl, and a boy with odd elbows, he noticed where Deku had gone to sit. Deku was sitting with a big guy with glasses who waved his arms around like a robot, a brown-haired girl with round, pink cheeks, and a boy with half red and half white hair. His head kinda looked like a Pokéball.
It was odd to see Deku sitting with friends. He hadn't had friends since Katsuki cut him off. Katsuki chose not to dwell on this.
"By the way, Bakugou, this is Ashido and Sero," Kaminari said.
Katsuki grunted in response and started eating.
"So, Blasty, what did you get up to with Midoriya?" Ashido asked with a mischievous glint in her eye.
"None of your business," Katsuki snapped.
"There's always something going on between you two, eh?" Sero commented, grinning.
What did he mean by that? No! Not thinking about that. Elbow Boy must be referring to how Katsuki's teenage self helps Deku out with his training. But this conversation was not going the way Katsuki wanted it to go. He wanted a little space from Deku right now, not for others to butt in on their... relationship? He didn't know what to call them.
"What are all your quirks anyway?" he asked around a mouthful of rice.
Getting the hint, Kirishima declared, "My skin hardens so that I can withstand even your blasts, Bakugou." He hardened the skin covering his left hand and forearm to demonstrate.
"I can secrete acid!" Mina exclaimed while corroding a paper napkin she held in her hand.
"My elbows shoot tape," Sero said while pulling a little bit of said tape out from an elbow.
"Hmph. Maybe after dinner, you can show me your quirks for real."
"Yeah! We can go outside and spar a bit! Great idea, bro!" Kirishima enthused.
"We can see if Kacchan's combat sense is innate or if he developed it more recently," Kaminari said with a smirk.
"I've always been great, Sparkplug!"
Katsuki wolfed down his dinner, eager to show these extras what he could do. He noticed that everyone else was putting their dishes in a dishwasher and followed suit.
"Come on!" he called as he raced to go outside. The four idiots followed and they began a round-robin set of sparring where Katsuki was matched up against each of them.
He did his best, putting everything he had into it. He knew he was at a size and experience disadvantage by being between 8 and 9 years younger than the teens, but he'd been training for this. If he could beat kids three years older than him who intended to hurt him, he could handle sparring with high schoolers.
During his matchup with Sero, a crowd of their classmates had gathered, a few of them had even broken off in pairs to do some sparring themselves. Red eyes briefly met green and Katsuki felt a surge of energy, landing a blast on Sero's side.
"Oof! I yield, little man! You got me." Sero held up his hands in surrender.
Katsuki gave a feral grin, held out his hands, and let sparks dance across his palms. "Who's next?" he demanded.
He looked at Deku again and called, "Deku! Let's see this so-called quirk of yours!"
Izuku was impressed. Obviously, 7-year-old Kacchan lacked the control, finesse, and experience 16-year-old Kacchan had, but he was still amazing for his age. Now that Kacchan was challenging him to spar, Izuku felt a little apprehensive. He couldn't go all out as he would with Kacchan normally, right? But refusing would tear down the progress they'd made.
Izuku remembered the sports festival and how angry Kacchan had gotten when Todoroki-kun hadn't used his fire. He'd refused to accept first place. During the fight at Ground Beta, Kacchan had almost seemed disappointed he won and asked Izuku why he'd lost when he had All Might's power. Feeling determined now, Izuku nodded and stepped forward as a grin spread across his face.
Katsuki saw Deku's face go from uncertainty to determination and was thrilled by it.
"Midoriya-kun! Are you sure this is the best idea?" the glasses guy asked with a robotic chop of his arm.
"Can it, Four-Eyes!"
"It's fine Iida-kun, I know what I'm doing. It's just sparring," Izuku placated.
Iida sighed and nodded at Izuku.
Deku's already bright eyes started glowing as green lightning sparked all around his body.
"Come at me, Kacchan!"
Katsuki lunged forward with his signature right hook, but Deku anticipated him and dodged way faster than Katsuki was expecting. Surprised by the speed, Katsuki used the momentum from his punch to turn and kick with his left. Deku blocked and reached out to grab Katsuki, but he used his explosions to blast away and keep his distance. Deku had definitely fought his more experienced self before and was using that knowledge against him now. Deku always had been analytical and observant.
They traded a few more blows and the fight came to an end when Deku pinned him to the ground, effectively immobilizing him. Katsuki stared up at Deku and couldn't stop smiling like a madman.
"My older self's help is paying off, Deku. Maybe you're not completely hopeless after all."
Katsuki wasn't disappointed by this loss, surprisingly enough. Maybe it was the knowledge that Deku was improving with his help. Maybe it was because he knew Deku hadn't held back. Maybe it was because Deku moved with confidence and skill he'd never shown before and Katsuki preferred seeing Deku like that than as a useless 7-year-old.
Deku smiled and let him go. He stood up, pleased that Deku hadn't tried to help him up.
Now, he needed a win.
"NEXT!"
After a few more rounds, he finished off with a spectacular victory against that navel laser guy, who could use some more quirkless combat practice in Katsuki's opinion. They all went back inside and decided to have a movie night, seeing as it was a Saturday.
Yaoyorozu, ever the perfect hostess, suggested, "Since Bakugou-san is something of a guest right now, how about we have him choose the movie?"
"ALL MIGHT!" Katsuki yelled, always happy to make group decisions.
Everyone settled in on the couches and a newer All Might movie that 7-year-old Katsuki wouldn't have seen was put on the screen. Katsuki sat at the end of one couch with Kirishima next to him. Deku was on another couch nearby with Pokéball Head. Turned out Half and Half had a pretty impressive quirk, which pissed off Katsuki. It pissed him off even more that Deku was friends with the guy.
"... Wastashi na kita!"
Katsuki redirected his attention to the movie, set those feelings aside for now, and let the joy of watching All Might win wash over him.
After the movie was over, Katsuki was tired. It was 21:00, way past his bedtime! He yawned, went up to his room, got ready for bed, and passed out.
When Katsuki woke up the next morning, still 7 years old, he thought about the day before some more.
Why wasn't he angry at Deku anymore? He'd been pissed off at the little dweeb for years. Had he really been swayed by teenage Deku's words and actions? It seemed like Deku didn't look down on him anymore, and apparently never had if his words could be believed. He fought Katsuki full out yesterday, despite the age and experience difference, and he didn't help Katsuki up afterward. If Deku didn't look down on him according to his words and actions, then how could Katsuki not believe him?
He also had to consider his own teenage self's actions. He knew all about Deku's quirk situation; Deku hadn't withheld information from him. Big Katsuki recognized Deku and was helping him with his quirk. He and Deku must have had a similar conversation where Deku told Katsuki he didn't look down on him and his older self believed it.
Just because he avoided Deku these days in elementary school didn't mean he didn't keep tabs on the dork. Of all the kids in their neighbourhood gang, Katsuki had preferred Deku's attention and praise more than the others for some reason. When they were 4, and it was just the two of them playing heroes or geeking out about All Might, Katsuki had fun; perhaps even more fun than when they were in a group.
He always wanted to show off for Deku, receive Deku's praise, and demonstrate how great he was. Katsuki enjoyed the contrast in ability between him and Deku. He could skip a stone 7 times; Deku couldn't skip stones at all. Katsuki could read kanji, enough to see that Izuku and Deku were a pun; something Deku had never noticed. Katsuki could keep a ball up in the air with his head, feet, chest, and knees; whereas it just bounced off Deku's head and onto the ground. Katsuki was clearly superior and he relished having Deku witness his greatness.
That's why it had pissed him off so much when Deku offered to help him up at the river. Time and time again, it had been demonstrated that Katsuki was strong where Deku was weak, yet Deku had dared to imply Katsuki could have been hurt. Deku's praise and admiration had meant the most to Katsuki; Deku must have never meant it if he thought Katsuki could be weak.
But Katsuki had apparently been wrong to see things that way all this time.
Now, Deku could compete with him. He was a challenge and Katsuki never backed down from a challenge.
If there was anything Katsuki was good at, and he was good at A LOT, let's be honest, it was observing the world around him, processing that information quickly, incorporating it, and acting accordingly. Deku didn't look down on him, his teenage self had acknowledged Deku as a proper rival, and he liked having Deku's eyes on him. So Deku was no longer someone to be avoided.
Now that things had settled in his mind, Katsuki got out of bed and went to the bathroom to start his day. In the changing area before the showers, Deku was shirtless and talking to Kirishima. Katsuki could now fully appreciate how much the nerd's body had changed, but then he saw a large patch of discoloured skin on his right arm. Deku had been wearing a long-sleeved shirt the day before so Katsuki had only seen the scars on his hands. This ruddy brown patch looked awful and like acquiring it must have been painful. It made him think of how Deku always pushed himself too far and didn't think about his own well-being when protecting other kids from bullies like Katsuki. Was that injury also from his quirk?
"Good morning, Kacchan!" Deku greeted him brightly.
"Hmph."
Katsuki went to the sink to brush his teeth. Seeing that scar made him feel uneasy. Deku was more capable now, but with that self-sacrificial nature of his... that couldn't be a good combination. No wonder his older self was keeping an eye on Deku.
"Die, germs!"
Katsuki finished brushing his teeth, stripped off his clothes without shame, showered, and went back to his room in a towel to change. Soon, it would be 24 hours since his transformation, so he decided to dress in a set of his teenage self's clothes. When he changed back into a teenager, he might be around people and he'd outgrow the kid-sized clothes. While he didn't especially care about being naked around others, the girls would probably have something to say, and he didn't want any of those extras talking about him in that context. He wouldn't give them the satisfaction.
Katsuki figured he'd normally do homework or study on a Sunday, but as smart as Katsuki was, he wasn't able to do high school-level work at this stage. He decided to go down to the common room to play video games and see if this quirk wore off anytime soon.
Deku, Pokéball head, and Sero were in the common room and happened to be playing Mario Kart, one of Katsuki's favourites.
"Losers, I'm joining the next game," Katsuki declared as he pointedly plopped down onto the large couch between Deku and Half and Half. Sero was on the other side of Pokéball. "Deku, have you gotten any better?"
"You'd be surprised, Kacchan. By the way, have you met Todoroki-kun?"
Huh. So that was Pokéball's name. Endeavor's son? The red hair and blue eye matched. Not that it mattered, of course.
Katsuki just grunted in response.
"Hello, Bakugou. We're friends," Todoroki said with a neutral expression on his face. Behind him, a mischievous grin spread across Sero's face.
"AS IF I'D BE FRIENDS WITH SOME HALF AND HALF WEIRDO LIKE YOU!"
Sero burst out laughing, Deku smiled and sighed to himself while Todoroki just shrugged.
"You don't have to yell, best friend, I'm sitting right next to you," Todoroki said in his usual deadpan tone.
Katsuki grabbed the free controller and was ready to kill everybody! He'd blue shell them all to hell!
"LET'S DO THIS!"
Izuku had indeed improved and, for the first time ever, gave Kacchan a run for his money. Izuku also noticed how Todoroki-kun and Sero-kun had been playfully elbowing each other and was happy for his friend. Obviously, with Sero-kun's prodigious elbows, he often won their little elbow wars, but it was brave of Todoroki-kun to challenge the king. He knew they shared manga and went to the store together sometimes; it was amazing to see Todoroki-kun open up to people after his difficult past.
Katsuki was holding up well, but it was obvious these teenagers he was up against had more experience and dirty tricks up their sleeves than he did. He was actually learning a lot of new strategies. He hoped he already knew these tricks and that he dominated normally.
"Just wait 'til I'm big again! You're all getting a serious pounding!" Katsuki threatened.
Sero guffawed, "Phrasing!" but he only received puzzled looks from Todoroki and Deku and a confused, irritated glare from Katsuki.
Sero sighed. "My talents are wasted on you three. Where's Kaminari when you need him?"
At the same time, Todoroki said, "I think you're very talented," while Katsuki scoffed, "What talent?"
They played a few more rounds when all of a sudden, Katsuki felt that tingling sensation. He filled out the clothes that had previously been hanging off him, his eye level raised up in height, and he was closer in proximity to Deku and Todoroki.
He was back to normal.
Katsuki sat in a daze for a few moments while the memories of the past 24 hours washed over him.
Izuku was relieved to see teenage Kacchan again! As wonderful as it had been to experience little Kacchan on better terms than what they'd been as actual 7-year-olds, he preferred it when Kacchan was as he should be.
"Kacchan?" Izuku asked with a look of concern. He knew Kacchan wouldn't appreciate it, yet he couldn't help but ask, "Are you o-"
"Don't even finish that sentence, Deku. I'm fine, just tired. Growing about 9 years in the span of a few seconds is fucking exhausting," he grumbled.
Katsuki was only half lying. He truly was tired and could use a nap, but what he really needed was some space to be with his thoughts again. While Katsuki was working on improving his relationship with Deku, he didn't really hang out with him casually like this, playing video games as he had just been. Seven-year-old him had no qualms about it but his teenage self had done things the 7-year-old didn't know about.
Katsuki stood up and said, "I'll let Aizawa and my parents know the brat's quirk has worn off."
"See you later, Kacchan," Izuku said, looking nervous but hopeful. It was fun playing video games with him! He hoped he and teenaged Kacchan could do it again sometime soon.
"Bye, Bakugou," Sero and Todoroki said in unison.
Katsuki waved a hand lazily in their general direction, started toward the elevator, and sent off those quick texts to Aizawa and his parents. When Katsuki got back to his room, he flopped down onto the bed, put his arms beneath his head, and allowed those words to ring in his ears.
"When I'm in a fight, I think about what you would do and it gives me strength."