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Katsuki wishes he could blame this on a villain attack. God knows it’d be less humiliating.
But no, he doesn’t even have the right of blaming this on one of those dumbass shitty villains. No, this happened because shitty Deku didn’t know when to take a fucking break for once in his life, and just had to jump in the middle of a quirk fight between a bunch of middle schoolers.
The result?
A dumb fucking child clinging to his legs and hiding from the rest of their fucking busybody class.
“Oh my God, he’s so cute!” That was invisible whatever-her-name-was. “Can I cuddle him, oh my God!”
“No way, Tooru!” Round Face -Uraraka?- butts in. “Deku’s my best friend, I totally get first cuddles!”
Shitty Deku is still hiding behind his legs, and Katsuki is this close to just blasting out of the place and just going back to his dorm and flat out hiding until this shit blows over. Glasses or Icyhot or one of shitty Deku’s other groupies can take care of this dumb kid until shitty Deku’s back to his normal, shitnerd self.
Then Katsuki actually tries walking away and is immediately reminded why he didn’t do it earlier.
“Kacchan? Kacchan, where are you going- Ka-Kacchan, don’t leave me alone- Kacchan!”
Why the fuck did shitty Deku have to be so fucking vocal as a four year old? Which fucking four year old even spoke so much, for God’s sake!
Katsuki will never admit it, but the hurt in that childish voice pulls him back to Deku’s side before he can even think otherwise. It doesn’t help that all his classmates are glaring at him for making the kid panic.
“Jesus, kid,” he grumbles as he levels with Deku again. “Why the fuck are you so fucking needy-”
Deku gasps, eyes wide. “Kacchan said a bad word!”
Kirishima gasps in time with Deku, and lunges forward to slap a palm over Katsuki’s mouth. Uraraka kneels down in front of Deku and regards him with serious eyes. “Never repeat that, okay? Kacchan is bad, don’t follow him.”
Deku, that little shit, just stares right back at Round Face and nods along.
Katsuki growls at that, and the little explosions that spark across his palms when he tries to wrestle Shitty Hair’s hands away from his face do nothing to deter the other boy, who just hardens his hands and holds on.
“Fuck off, Shitty Hair,” he snarls, muffled by the hand over his mouth. A part of him wants to just lick or bite Shitty-shima’s hand until he lets go, like a little kid, but the bigger part of him wants to maintain whatever dignity he has left, so he just keeps aiming explosions at the other boy instead.
Kirishima looks him in the eye then, and Katsuki swears the other boy is pouting. “I’m not letting you go until you promise not to curse in front of the kid.”
Katsuki growls, and aims an explosion at Kirishima’s face. The other boy just hardens his skin, and holds his gaze.
Katsuki doesn’t want to let it go, but finally he caves, shoulders slumping almost unnoticeably as he grumbles a forced, “Fine.”
The other boy grins then, his usual sharp-toothed smile that looks a hell a lot less threatening than it should, and lets him go.
Immediately, Deku is on him, wrapping short arms around his leg and grinning up at him with that twice-bedamned smile. Why isn’t he kicking the kid off again?
Oh, right. Because the kid is four, and that would probably injure him enough that even Katsuki has second thoughts about it. He has boundaries, okay?
“Kacchan, wow, you’re so tall now!” Deku is looking up at him with those goddamned huge puppy eyes and bright smile, and goddammit, he’s already had to deal with this once, why does he have to go through this fucking sunshine shit again? Did the universe truly hate him this much?
“Do I get tall too? Oh, oh, do we both become great heroes, are we gonna become, like, the bestest heroes? Kacchan, Kacchan, this is so great!”
Katsuki groans. “Why me? Why the fu- freak.”
Behind him, Kirishima mumbles something unheard, and then Yaoyorozu is shoving a glass jar at him, and damned Earphone Girl is smirking at him.
“Swear Jar,” is all she says, and Katsuki’s palms pop.
“What the he-”
“Swear Jar!” Kirishima cries. “We’ll let you off this time because you didn’t actually complete the sentence, but next time, it’s a hundred yen per swear.”
“Who made you the f- sh- ugh!”
Kirishima hides a snort behind his hand, and Katsuki shoves a hand in his face and explodes. “Suck it, Shark Week!”
“Shark?” Deku says, perking up and staring at Kirishima. “Oh, oh, it's your teeth, they’re like a shark’s, Kacchan’s so smart with names!”
Deku turns wide, admiring eyes on him, and Katsuki huffs, slapping a palm to his face to hide the way heat rushes to his cheeks.
His classmates snicker, and the palm that isn’t pressed to his face crackles. Fuck them, why is his class so freaking annoying?
Why does he have to deal with shitty baby Deku for, what, the next week?
Ugh.
When they finally manage to get some semblance of control and head back to the dorms, they get waylaid at the entrance, because the moment Deku steps past the Yuuei entrance alarms start blaring and the metal gate comes slamming down, and it’s only because Icyhot sends a wave of ice down to knock Deku out of the way that the kid isn’t crushed by the gate.
And, wow, wouldn’t that be a way to go. But Katsuki instinctively dives to catch the kid when Todoroki’s ice sends him flying, and, well, he’s not exactly surprised when Deku falls in his arms and clings to him like a limpet, tears running down his cheeks. His eyes are wide with shock, and the damned alarms aren’t exactly helping when they keep shrieking.
“K-Kacchan,” Deku hiccups, burying his face in Katsuki’s shirt, and Katsuki can feel his shirt dampening. He sighs, and rolls his eyes, but lifts a hand to pat gingerly at Deku’s trembling back.
“Stop crying, useless Deku,” he grits out, but without the aggression that the statement usually contains.
The kid doesn’t stop, and it goes on like this for a minute or so before Katsuki shoves the kid at Shitty Hair and stalks off towards the main Yuuei building.
Deku hiccups and gives an aborted cry of, “Kacch-” before Shitty Hair hefts him into his arms and Frog Girl calms him.
Katsuki continues storming towards the main building, and is met by Aizawa and Principal Nedzu along the way, both visibly worried about the alarms.
Aizawa takes a single look at his face and sighs, closing his eyes and pinching the bridge of his nose. “It’s the problem child again, isn’t it.”
Katsuki growls. “Shitty Deku got turned into a kid, the system doesn’t fucking recognise him.”
Nedzu smiles, and hops from Aizawa’s shoulder to Katsuki’s, and Katsuki has to restrain himself from blowing up the principal. “Well, we can easily fix that!”
It takes maybe another five minutes to key kid Deku’s signature into the system, matching it up to the Yuuei ID that’s still in Deku’s pocket. The moment the alarms stop blaring and the barrier comes back up, allowing the rest of the class that had been trapped behind it through the entranceway, Deku squirms his way out of Kirishima’s grip and runs over to Katsuki, eyes wide. “Kacchan, Kacchan, that was so scary, why was it so loud, did I do something wrong, Kacchan!”
“For fu- freak’s sake, why are you so mouthy,” Katsuki mumbles, but sighs and explains anyway, huffing in frustration.
Behind him, Raccoon Eyes stage whispers, “Oh my god, that’s so freaking cute,” and Katsuki draws in a deep breath and digs his nails into his palm to keep from exploding Ashido’s face off.
It’s a few days later that word gets around school that Midoriya of Class 2-A has been turned back into a child temporarily, and Shinsou, Kendou and Tetsutetsu turn up on the doorstep of their dorm carrying bags full of children’s clothing, soft toys and other odds and ends.
“We thought you might want some help with Midoriya,” Kendou explains, hefting the bag that’s so big that even in her enlarged hand it doesn’t look disproportionately small. “Most of the clothes are from Tetsu’s little siblings, and the soft toys from Shinsou and Pony, the rest our class got together to collect for you guys.”
Iida and Yaoyorozu smile simultaneously, and Iida bows at the waist, spewing thanks profusely while Yaoyorozu hugs Kendou and smiles brightly at Tetsutetsu and Shinsou.
Kirishima slings an arm around Tetsutetsu’s shoulders and slugs him in the arm with a hardened fist, grinning a shark-toothed grin when hardened skin meets metal. “Helping others without prompting, that’s so freaking manly, dude!”
“Bro, I know!,” Tetsutetsu says, flicking a spike of red hair and laughing when Kirishima pouts. “Where’s kid Midoriya anyway?”
“In his room- the kid is obssessed with All Might, bro, even more so than he is now, dude! Man, I didn’t think you could be a bigger fanboy than sixteen year old Midoriya, but this four year old him really takes the cake!”
Shinsou comes over at that, arching a brow, the slightest smile playing at his lips. “You didn’t think kid Midoriya would be a bigger fanboy than present Midoriya? I have to say, it’s hard to believe, but pretty logical once you think about it.”
Tetsutetsu and Kirishima hum in consideration, then nod in synchronisation.
“I hope you didn’t leave him alone, at least,” Shinsou says then. “Midoriya’s All Might collection isn’t exactly the safest place to be for a four year old.”
Kirishima grins. “Don’t worry, dude, Bakubro’s keeping a close eye on him!”
The fact that even Shinsou visibly starts at that statement is telling. “You left Bakugou in charge of a four year old Midoriya?”
Kirishima shrugs. “Weird, right? But, man, Bakubro’s really good with him, though! Like, I know he’ll never admit it but my bro has a good heart, dude, he’s so manly, oh my god.”
Tetsutetsu arches an eyebrow, a grin playing at his lips. “Dude, I know you’ve got like a giant crush on him, you sure it’s not clouding your judgement?”
Kirishima frowns at him. “ Not manly, dude! That’s a secret!”
Tetsutetsu winces. “At least no one heard?”
Shinsou arches a brow. “I’m right here.”
Kirishima pouts harder, and Tetsutetsu winces again.
Shinsou smiles then, a small, wry grin. “Don’t worry, I won’t tell anyone.”
Kirishima breathes a sigh of relief, and Shinsou stares him in the eye and says, “But I have to ask, Bakugou?"
Kirishima flushes. “He’s really manly, okay? And he’s secretly a softie and he can be really nice sometimes!”
Then Todoroki sits up from where he’d been lying on the common room sofa, a wry grin playing at his lips. “You should see him with kid Izuku, I don’t blame you, Kirishima.”
Kirishima squawks. “Todoroki! How long have you been there, oh my god, what the heck, not manly, dude!”
Todoroki huffs an amused breath. “And he’s not bad looking, I mean.”
Kirishima’s eyes widen. “Dude, you better not be competing with me for Bakubro’s attention.”
Todoroki snorts then, and rolls his eyes. “He’s all yours, Kirishima, blond with anger management issues isn’t my type.”
“What is your type, bro?” Tetsutetsu asks, and Todoroki just raises an eyebrow.
Kirishima grins. “Lemme guess, short and green and excitable.”
Todoroki’s nose scrunches. “Am I that obvious?”
“Don’t worry, bro, I don’t think Midoriya knows!” Kirishima assures, grinning, before turning back to Shinsou and Tetsutetsu. “Anyway, guys, who wants to go see Bakubro being a complete mum friend!”
“I’m always up for getting more blackmail on Bakugou,” Todoroki deadpans, pushing himself up from the sofa.
“Likewise,” Shinsou says. “Count me in.”
The first thing they hear when they exit the elevator on the second floor is what sounds like a higher-pitched, even more excitable version of Midoriya’s voice.
“Kacchan, Kacchan, Kacchan, what edition is this? Oh, All Might changes his hero costume? Ahh, when, when, when, Kacchan, what’s the future like, is All Might still number one, is he even more awesome, Kacchan, come on, Kacchannn-”
“Shut up, nerd,” comes Bakugou’s voice, low and growling, and Shinsou turns a skeptical look on Kirishima.
“Good with him?” Shinsou quotes, and Kirishima grins.
“Just wait!”
A sigh, echoing down the corridor -and, wow, they should really tell the teachers how thin the walls of the dorms are, if they can hear everything so clearly- and then Bakugou’s voice, resigned. “Yes, All Might changed his costume. It was when we were nine. That figurine is the sixth edition, it’s one of the few you have that I don’t. I’m still upset about that, by the way, you snatched up the last one just before the old hag was gonna buy it for me.”
“Oh no, Kacchan, I’m sorry, are you angry, please don’t explode me-”
The crackle of the following explosion is softer than it should be, and both Shinsou and Tetsutetsu take an aborted step toward the door, eyes wide.
Then Bakugou’s voice comes resonating down the hall, a half-shouted, “For f- God’s sake, freaking Deku, what kind of person do you think I am, I’m not gonna blow up a fu-freaking four year old!”
Todoroki chuckles beside Kirishima. “Now, that’s more like the Bakugou I know. Although he usually wouldn’t hesitate to blow up Izuku.”
Kirishima shrugs. “Nah, Bakubro has lines he won’t cross too, and he wouldn’t willingly hurt a little kid, even if the kid is Midoriya.”
Todoroki shrugs. “Well, I guess the provisional license extra training we had last year told me that much. He’s surprisingly good with kids.”
Shinsou’s lips twist a little, and his tone is dubious even as he says, “If you guys think so. Anyway, come on, let’s go burst in on Bakugou actually being a decent person and watch as he reverts to asshole state.”
Kirishima makes a brief sound of protest, but heads in the direction of Midoriya’s dorm anyway.
Five days into the whole event, it all goes to shit.
And, as usual, when it’s not Katsuki’s fault it’s fucking Monoma Neito’s fault. Fucking copycat asshole shithead wannabe.
“Heard the little bone-breaking class A loser got himself turned into a little kid,” copycat asshole starts as he saunters up to their table during lunch, smirking.
Katsuki has to physically restrain himself from exploding the bastard’s face, and even then it takes both Uraraka’s threat to float him off to outer space and Kirishima’s hardened hand holding him down to stop him from actually trying to kill the guy.
“What’s he like as little kid, huh? Must be a whiny little crybaby, breaking his little baby bones all the time- oh, wait, unless the rumours are true and he didn’t even have his quirk yet, huh? Little quirkless loser,” Monoma scoffs, and then a lot of different things happen at once.
First, Deku stares at copyfucker, uncomprehending, for all of ten seconds. Then Deku bursts into tears. As usual. Again. Like always.
Why the fuck.
But Katsuki’s grown up with the useless crybaby, and despite not giving a fuck about him usually, Katsuki knows the difference between Deku’s usual tears and these ones.
These ones are silent, and shocked, all visual and no audio. It’s like watching a show on mute. The tears are falling fast and continuous, a neverending stream down his cheeks, but Deku is completely silent. His eyes are wide and unseeing, and if Katsuki didn’t know any better he’d say Deku was in shock.
But no, these are Deku’s genuinely distressed tears. He’s never actually seen Deku cry like this many times. The number of times he’s seen this happen he can count on one hand. Once, when they’d been really, really young, and Deku’s father had left. Another time, when they were four, and Deku and his mum had walked past Katsuki on the playground, on their way home.
Katsuki hadn’t known it at the time, but that had been the day that Deku had come home from the doctor’s and been told that he was quirkless.
But after that day Katsuki had never seen Deku cry like that ever again.
Except now.
Fuck.
If Katsuki had known just how much being deemed quirkless had affected the kid, he wouldn’t have- okay, actually, kid him (and preteen him) was a complete and utter dickbag. He knew this. He’d accepted it. Yeah, kid him would probably still have bullied Deku for it. Fuck.
But to see Deku crying like that again, and see fucking copycat asshole Monoma Neito be the cause of it? Yeah, Katsuki was furious.
He launched himself at Monoma, explosions already sounding, and he feels the recoil burn in his forearms as he pushes the explosions stronger and stronger. It’s a good burn, a burn that means he’s strong, a burn that means this fucker is going to pay.
Then there’s a fucking ice wall between them and Katsuki’s fucking floating.
Fuck. Round Face. And Icyhot, probably, unless the copy asshole managed to get Halfie’s quirk, which doesn’t seem very possible, seeing as Todoroki is way out of touching distance.
Then Katsuki sees the the ice is more jagged than usual, like it always is when Icyhot actually gets emotions, and it’s not just an ice wall, it’s an ice prison which encases Monoma from mouth to toe. Good. Fucking Icyhot covered his mouth too, Katsuki can appreciate good work when he sees it.
“Round Fa- Uraraka,” Katsuki yells down, fists clenched as he actively tries to tone down the aggression in his voice. “Can you let me the f- freak down already? I swear to god I won’t explode copycat’s face off.”
Uraraka’s gaze meets his, and she must see something in his face that Katsuki doesn’t know about, because she nods and presses her fingertips together, and then gravity is taking hold of Katsuki again.
A few well-timed explosions later, Katsuki is back on his feet, glaring at Monoma while his classmates try to comfort Deku.
Deku doesn’t stop crying.
A moment later Yaoyorozu is coming back with that orange haired giant-handed whatever-her-name-is president of class B in tow, and the other girl takes one look at the scene -Deku still sobbing silently, entire body trembling, and copy asshole frozen almost entirely- and shakes her head, sighing.
“Okay, you know what,” she says, lips thinned. “I’m going to leave Monoma like this and let him wait patiently to thaw out. It’s about time he learned to stop picking a fight with you guys anyway. Kan-sensei will understand when I tell him.”
Deku’s still crying, and at this point even Uraraka seems discomfited and out of her depth- Iida and Todoroki have long started shifting uncomfortably and awkwardly patting the kid on the back now, even if they seem to be taking turns trying to hug him.
Uraraka shoots him a vaguely distressed look, and he glares back, because what the heck does Round Face think he can do?
But the crying’s starting to grate on his nerves, so he marches forward and squats down in front of Deku, huffing.
“Listen, shitty Deku, I know you’re really fu-freaking upset about the whole don’t-have-a-quirk thing but for god’s sake, get yourself together, will you? I know you’re not freaking dumb, use the brain of yours, if you didn’t have a quirk would you even be here, you dumb nerd? We’ve already established you’re a freaking Yuuei student, haven’t we, you dumb freak? Get your shit together.”
Well, at least he’s stopped crying now. Deku’s staring at him, visibly stunned, eyes still brimming with tears, but his shoulders have stopped shaking and he doesn’t look quite so upset any longer.
“Re-Really?” He stammers, and Katsuki groans inwardly, rolling his eyes. He eyes Deku, not so much a glare as an exasperated stare, and Deku shuts up, eyes lighting up.
Katsuki just growls and stomps away.
All those dumb fictional stories on random deaging lie. Reverting back to normal doesn’t conveniently happen overnight where the affected person goes to sleep as a kid, wakes up, and hooray, they’re back to normal.
Nope, freaking Deku changes back to normal in the middle of class, between one blink and another. Katsuki is just grateful that his kid clothes were already baggy to begin with, and that Deku himself wasn’t exactly huge, because as it is only his shirt rips, and his pants at least still hide enough to be considered decent.
Still, it’s more of the shitty nerd than Katsuki has ever wanted to see.
Aizawa just sighs and rolls himself into his sleeping bag after telling Iida and Yaoyorozu to deal with it, and for once in his life Katsuki might actually appreciate one of his classmates, because Yaoyorozu immediately creates a replica of Deku’s usual uniform and hands it to him, eyes averted.
Icyhot is steaming up the back of the classroom, Katsuki can feel the mugginess from where he is, and he growls. He would stand up and blast Todoroki’s face off, but that would require him to actually walk past Deku, who’s still seated half-dressed on the floor, stunned, and yeah, Katsuki’s not touching that with a ten foot pole.
After Deku gets dressed class finally starts up again and Katsuki is really fucking glad everything’s back to normal. The past week of baby Deku sticking to him like glue were ridiculous -no, he absolutely did not like them at all- and Katsuki’s just happy to be finally rid of him.
No, really, he is. He definitely doesn’t expect that annoying little kid voice to call “Kacchan!” every few hours, and definitely doesn’t brace himself for a tiny person running full force at him whenever something unexpected happens.
He doesn’t. Definitely not.
So when Deku chirps a, “Thank you for looking after me while I was under the effects of those quirks, Kacchan!” at the end of class, Katsuki turns and shoves a palm in his face, convenient blowing the nerd up.
And Katsuki definitely doesn't smile when he picks up the thank you bento and note outside his dorm door the next day.