They first hear it at 1pm on a Saturday afternoon - thumping bass, synthetic cords, and a disembodied voice demanding that they flip on their back and get ready for stomach crunches.
"What the hell is that?" Kaminari says, looking around the lounge area for the source.
Ashido joins him, both leaving their chairs to hunt around like there's a hidden speaker somewhere that will be found if only they toss enough couch cushions onto the floor. Kirishima stays where he is, bobbing his head to the beat with a trail of noodles hanging out of his mouth.
Katsuki continues to eat his lunch; heavy on spice and light on everything else. He knows exactly what that noise is and what it means, and he wants no part in it.
It goes a little bit like this:
Katsuki has only ever managed to ignore Deku's existence for ten months in the entire time they've known each other.
Ten months. In sixteen years.
There's a thing with a villain in there, and help where it wasn't needed, and Katsuki doesn't like to think too much on the reason why he couldn't stand to look at Deku for most of a year.
He also doesn't like thinking about it because then he'll have to admit that a good portion of those ten months were spent dwelling on Deku and his stupid and futile hero complex instead of interacting with him, and he needs this distinction.
One minute, Deku is a weedy, weak little quirkless nerd with the constitution of weepy jello, and then ten months later the little bastard is pumping iron at his desk and tearing the seams of his gym clothes every time he moves.
Katsuki has entirely no idea what happened, and he doesn't particularly care. He'll be getting into Yuuei, and Deku can go on to be world bodybuilder champion for all he gives a shit, so long as it's not near him.
Of course, that doesn't quite happen, and he's forced to deal with Deku's existence in his life for a little longer than planned.
Deku, who lives in the same neighbourhood and apparently enjoys running fucking marathons around it and doing chin-ups in the park.
Katsuki changes his route to be twice as gruelling and signs up to a gym in the next town over.
The first time Katsuki is introduced to Deku's idea of workout music, it's because his mother grabs him by the ear and drags him over to Deku's apartment complex. "To congratulate Izuku on getting into Yuuei with you," she says, but Katsuki suspects she just wants to gloat about his own acceptance to someone who understands the odds.
Deku answers the door with a barbell in one hand, another held between his teeth, and the most horrific synthpop Katsuki has ever heard blasting from deeper in the apartment.
"Mm-ffugou?" he says and spits the barbell back into his free hand. "And... Kacchan? Uh, hi?"
"Look at you! All grown up," his mother exclaims, pulling Deku into a chokehold right around the same time Deku's mother rounds the corner to see what all the fuss is about. There's a whole lot of pleasantries and smothered choking and at some point tea and snacks make an appearance.
Katsuki spends this time glaring and emphatically not congratulating Deku on anything.
Not on his expectedly terrible taste in music, and absolutely not on the unexpected amount of muscle he now seems to have.
The second time, and every time thereafter, has been a direct result of this new bullshit dorm situation they've been coerced into.
It's not as easy as just changing his routes and buying some solid earplugs, because Deku works out everywhere.
Katsuki comes down in the morning and he's there, doing sit-ups on the common room floor. He finds him doing lunges in the kitchen. Squats in the laundry. Stair climbing exercises up and down the stairwell. He's got a pair of fucking hand-grippers glued to his left hand at all times while his right does things like eating and cleaning and writing and probably even bathing.
Katsuki leaves the safety of his room to do literally anything and the little fuck is doing one-handed pushups in full view through the windows and attracting an audience while he does so.
"I bet he's as rock solid as you when you're using your quirk," Ashido remarks one day to Kirishima.
"I'll take that bet, on behalf of my pride as a man," Kirishima says, and goes outside to poke around at Deku's arms and stomach. He comes back in looking shaken.
Katsuki thinks that they could all stand to harden the fuck up to this sight.
Which brings him to now.
The only light Katsuki has in this whole clusterfuck of communal living is that he is separated from Deku by an entire floor. He has no idea if Deku's neighbours are constantly bombarded by the very best the 80's have to offer or not, and he doesn't give a fuck, because he can't hear it. Similarly, Deku seems to at least have enough presence of mind to keep that shit to himself when he's swanning himself around the building, either using earphones or going silent.
Katsuki doesn't know why he's chosen now to broadcast his personal mixtape to the world, but he's heard and seen this all before and he's not really in a rush to subject himself to it further.
"I like it," Kirishima says, because of course he does. "I gotta find out what this is."
"I think it's coming from out front," Ashido says, effectively taking point as the group all follow her outside. Katsuki is dragged along by Kirishima's surprisingly strong grip and his own infernal weakness.
He knows he doesn't want any of this, but he's also morbidly curious at what new kind of spectacle Deku is making of himself on their front lawn.
Katsuki squints as the sun hits his eyes and then freezes.
It turns out the spectacle is shamelessly holding himself perpendicular to a light post in rolled up sweatpants and a faded red tank. Underneath him sits a boombox and a scattering of onlookers.
"Focus your energy," the disembodied voice says, now identifiable as part of the track.
Katsuki's focusing, alright. On questions like why, and what the fuck, and who even asked for this? And also, a little bit, on those areas that look more defined than what Katsuki sees in his own mirror. But mostly, what the actual shitting fuck.
"A few of us wanted some workout tips," Sero says when Kaminari asks. "Midoriya's built like a little brick shithouse, y'know? Figures he'd know what to do about... this." He makes a gesture to encompass his lanky frame and then frowns. "Hey Midoriya, what is this supposed to be good for again?"
"Core muscles," Deku chirps, sounding bright and refreshed and not at all like he's hanging from a light post in a direction gravity never intended. "Upper body strength, too, I guess."
He holds himself there for another few seconds, looking effortless even as his muscles bulge and sweat very visibly pools in the dips of his body and darkens his shirt, before gracefully lowering himself down to the pavement to the sound of applause.
It reminds Katsuki of those clown knockoffs - acrobats? - that do freaky shit with their bodies instead of acting like the clumsy affronts to nature they're supposed to be.
Or maybe like strippers. Yeah, there's a pole involved and Todoroki's looking pretty into it; more like strippers.
Deku shrinks into himself with embarrassment - somehow, illogically, considering what they all just witnessed - and lifts the bottom of his shirt to wipe at his face.
Katsuki stares at the torso on full view; the wide shoulders and the strong calf muscles peeking out from the rolled up fabric and thinks shit.
He might be pretty into it, too.
The next morning finds Deku and half the class holding some kind of aerobics/yoga bullshit in the middle of the common area floor. The couches are pushed to the side and the television in the corner has been put... somewhere, replaced by the same shitty boombox from yesterday, playing the same shitty kind of music.
Katsuki shoves a spoonful of cereal in his mouth from his vantage point in the kitchen and tries really hard not to feel personally betrayed by the loose, oversized All Might t-shirt Deku is sporting.
"Outrageous," the song says, followed by heavy bass. Katsuki nods in silent agreement.
By the middle of the week, Deku has gained more followers into his cult-like workout mission, and the next time Katsuki gets a barbell under his ass instead of the soft couch cushions he's expecting, someone is going to be beat to death with exercise equipment.
Late Friday, he feels safe enough to wander down from his room in search of something to eat. From his observations, these little physical wellbeing shindigs tend to take place mostly in the mornings and occasionally the afternoons.
He walks down into a crowd hanging out on one side of the kitchen bench and Deku on the other, handing out dietary advice.
"He said whatever I'm doing seems to be working for me," Kirishima says dreamily. "You hear that, bro? Even Midoriya thinks you can't improve on perfection."
"I've seen you put pocky sticks on yakisoba bread," Katsuki says. "You're just a lost cause, like he is."
He nods towards Deku, who is the very picture of a lost cause behind his bench; he looks like a drowning man, begging for someone - anyone - to save him from his own self-made hell.
Serves him right for clearly knowing what he's doing, with a body like that, Katsuki thinks and makes a 180 to the entrance doors. There's a convenience store bento that'll still be less effort to get to than trying to make his way through that sad pile of body issues.
"What would you suggest for me?" Someone asks. "My quirk relies on sugar, but it does nothing for my waistline."
"Glucose before morose," Deku says faintly. "Stay true to your quirk, Rikidou-kun."
Saturday finds a delightful reprieve of any and all group exercise activities, because Katsuki stays in bed well into the afternoon, and then only leaves his room to hit up the gym.
The gym that was provided to them when they all moved on campus.
Why the fuck has Deku been flaunting himself all over the dorms when they have a dedicated gym.
"We have a gym for this shit!" Katsuki yells at Sundays weightlifting class. "Take your foamy, bullshit props and frilly mats and fucking use it!"
Deku looks at him stupidly, frozen mid-lunge with barbells held at half-mast. At least two people drop theirs; one on their own foot, if the unladylike swearing is anything to go by.
"Oh shit, yeah, we do," he says finally, pulling himself up to a stand and dropping his arms to hang at his sides. "I forgot about that."
"How do you forget an entire gym made for exactly this purpose?" Katsuki seethes. All that trashy audio assault and all those unwanted revelations he could have avoided; he would never have known how Deku stacks up against Greek statues. Which is well. He would never have known.
Deku shrugs casually, the weights in his hands making the muscles in his chest work. "I never had a gym before now, I guess. I just got used to doing this stuff around in normal places."
Normal places, like the local park in the neighbourhood they both live.
Katsuki would have probably known eventually.
Deku and his little fitness club all start packing up their shit, rolling up mats and placing weights in bags in preparation to move to the gym Katsuki reminded them of. The gym that's separate from the dorm building and thus not a place he's likely to encounter surprise Grecian physique whenever he leaves his room.
"Fuck it," he says, right as Deku is coincidentally bending down to pick up a bag. "Keep your plebeian normal places, it just means nobody's hogging my equipment."
The shitty music is just something Katsuki is going to have to live with.
Monday sees Katsuki entering a new kind of hell, as everyone in the locker room keeps sidetracking Deku to show off the barely visible results of their hard work. It's been ten minutes, and Deku has spent all of those minutes just uselessly holding onto his shirt instead of putting it on.
Ten minutes of flitting around and staring approvingly at every body in the place but Katsuki's.
It's insulting; he's insulted.
He doesn't need any damn approval, because Deku's opinion means dick to him, but Katsuki's a veritable showcase of physical perfection over here and it would be nice if it was appreciated, instead of being passed over for lesser abs.
"Touch me," Kaminari says to Deku. "I am firm, bro."
Deku slings his stupid shirt over his shoulder and reaches out a hand to poke at a pectoral. There's give where his finger digs into the weak, shapeless flesh of Kaminari's chest.
Katsuki's got all his clothes on; he doesn't need to stay here for this.
And if he purposely shoulder-checks the both of them on his way out, well, he's just demonstrating what firm should feel like.
For the next week, Katsuki gets used to routinely being subjected to lycra and sweatpants and everyone grabbing bits of each other to congratulate them on what they should have already had, this being the top fucking hero course for a line of work that begs some amount of physical fitness.
He comes down in the mornings and watches the yoga show while eating his breakfast, learns to look before he sits on anything, and has made his peace with every part of this bullshit fever dream being accompanied by the sounds of what he imagines a computer taking a dump would sound like.
He can deal with this, because the longer it goes on the more experimental about the workouts Deku seems to get and Katsuki has seen some interesting things. And also because there's now defined times that this shit goes down, and Katsuki can always work out on his own in his empty gym while they're at it.
The middle of a Sunday is not one of those typical times. Katsuki hears it as soon as he hits the stairwell, the deep thumping of a subwoofer reverberating around the walls and drilling into his skull, when all he wanted was some lunch and maybe, possibly, some quiet time after to study class materials instead of various parts of Deku.
He makes it all the way to ground level before he realises that the sound isn't even coming from there; he doubles back because if Deku's shit music taste is contagious he's not sure he can stand to let anyone in the building live.
He finds the source on the second floor - which he thinks is Deku's floor. Katsuki will forever deny the overwhelming sense of relief that hits him when he realises that it is Deku's floor, and the unholy cacophony is coming from behind Deku's door and nobody elses. Like Kirishima's, for a totally non-random example.
Katsuki doesn't even bother knocking, he just kicks it in.
He immediately regrets it.
"... Kacchan?" Deku says from where he's using the doorway to his bathroom to do chin-ups. Sweatily. Shirtlessly.
Deku stares back, still where he holds himself without even a fucking tremble in his limbs.
Katsuki thinks his everything is shaken and trembling.
"Do you ever fucking stop?!" Katsuki snaps and whirls around to make an exit. He'd slam the door too, but he's broken it; his only option for getting away from this sight is to leave this floor and the building entirely.
He goes to the real gym, with actual, functioning equipment to work off his frustration and finds that today is just a day where nothing is sticking to the accepted game plan.
Todoroki stares at him from across the otherwise deserted floor. Todoroki, who - like Katsuki - is more an observer than a participant in Deku's fitness hour.
"The hell are you doing here?" Katsuki snaps, feeling thwarted at every turn.
Todoroki just eyes the rowing machine with a sad little gesture and sighs. "I feel self-conscious in a group."
Katsuki grunts, because that's not what he'd meant when he asked. What he'd meant was what can I do to make you leave, and he himself does not a group make.
"Apparently Midoriya doesn't take personal clients," Todoroki continues, tapping at a weight with an air of dejection. "Offering to pay just seemed to make it worse."
"Stick a few yen down his pants and maybe he'll show you something," Katsuki says and heads towards the punching bags in the corner. He's got plans for those, and they all involve imagining Deku's face on each and every one of them.
Todoroki makes a considering noise from his corner and leaves him to it.
Another day, another locker room. Only this time, Deku spends an uncomfortable amount of time staring at Katsuki rather than at anybody else.
Katsuki tries not to preen too obviously.
Downward Dog, what a fucking joke of a position to put yourself in on purpose.
Deku meets his eyes from where he's bent over; Katsuki chokes on his granola.
"Cough it up!" Uraraka yells at him. "Put those core muscles to use, Bakugou!"
"Hey Midoriya," Kirishima says from somewhere in the middle of the pack, hand raised like they're in fucking class, "how do you feel about dance-aerobics?"
Deku looks interested.
Katsuki feels betrayed.
The next morning is best left buried deep, deep in Katsuki's subconscious. About as deep as the brand new circle of hell he's just discovered; the one that's just a loop of Deku enthusiastically wiggling himself around and singing "caught in a bad romance" high-pitched and off-key.
Deku catches him staring again mid-week and tells the rest to keep at it while he makes his way over. There's a confidence in his approach that Katsuki isn't used to seeing from him - or maybe that's just the effect of the cut-offs and tank failing to conceal the stored power in his body.
Post-revelation Katsuki kind of approves.
"You could join us," Deku says, leaning in just this side of uncomfortably close to be heard over the boombox. "You know, if you wanted to."
"I was born above your league," Katsuki sneers, insulted by the very suggestion that he wants or needs to gain anything he hasn't already got. He makes a wide sweep of his body with both hands as if to demonstrate. "The hell do you think you could do to improve on this, huh? You can't."
Deku treats himself to a cursory once-over and fails to look as impressed as he should be.
"I can think of a few things," he says with a raised eyebrow. "Offers always open, Kacchan."
That sounds like a challenge.
Not a challenge to join in, because that's what Deku wants and Katsuki refuses to give it to him. But a challenge to out-do the cocky little shit.
He stares at himself in the mirror and tries to pinpoint the flaws in his physique that Deku thinks he sees.
He can't find any.
He is a lean, mean, built machine.
Deku's eyes seem to find his at the top end of every sit-up; it doesn't even seem to matter that Katsuki shifts position every time it happens.
"Take off your clothes," the boombox plays loudly. "Don't be so shy."
Katsuki cuts his viewing short that day.
He's greeted the next day by the boombox spitting "tell me what you want so we can do just what you like," at him and Deku doing some weird lunge-dance move hybrid.
"You make me feel so la la la la," he sings, staring Katsuki dead in the eye.
"You make me feel so la la la la," the class group echoes back, staring at Deku.
Katsuki's feeling a little bit harassed and he's not even sure which direction it's coming from.
"I'll take it as it comes any way you choose to give it."
This is definitely some kind of subliminal harassment.
"You don't have to be alone anymore," Deku warbles and then pretends he's just singing along to the song and not leaning in to Katsuki's ear when he glares.
What is this now, overt harassment?
"I'm not joining your fucking shitty little workout groups," Katsuki yells back.
He secludes himself from any and all activities that may put him anywhere in range of exercise, shitty musical messages, and Deku over the next few days.
Outside of class hours, at any rate. It's a constant source of irritation to Katsuki that he can't just avoid Deku entirely; he's always there, even when he shouldn't be.
Sitting behind him. Staring. Clenching and unclenching those fucking hand-grippers when he thinks Aizawa isn't looking.
The least the little bastard could do is to not draw attention to his continual existence in Katsuki's life, because Katsuki himself has been historically bad at ignoring it.
And that was before he - almost, maybe - wanted him there.
Katsuki ate his breakfast staring at his blank bedroom wall this morning. It was boring as fuck.
Katsuki enters the kitchen early the next morning with his head held high and his uniform swapped out for sweats and the tightest tanktop he owns.
He's going to the actual, functioning gym and he's making damn sure Deku watches him go.
"Guys, I need to change the song," Deku says faintly.
Katsuki's out the door before he hears what it's changed to.
He does the same thing that afternoon, and it plays out as an almost exact repeat of the morning.
Katsuki catches the opening few lines of whatever monstrosity Deku has queued up for him before it's unceremoniously shut off with a scandalised yell from their class rep.
He gets to the deserted gym and has to stop and take a moment to parse it.
"Sexy boys," he whispers to himself in the silence.
Katsuki's starting to think the open offer is for something else entirely.
"I am a beautiful specimen of beefy manliness," Kirishima says, hiking a leg up on the locker room bench and flexing. "Look at me, bro, my natural body is outdoing my quirk; look at the magic of mutual encouragement."
"Your quirk is part of your natural body, dumbass," Katsuki snorts. "Encouragement is just bullshit speak for being too weak to do something yourself and you can shove it up your ass."
"Aw, c'mon," Kirishima whines, dropping the pose with a slump. "You're the only one, the last hold-out. Even Todoroki's done a few. Once he tried to pay Midoriya for his 'services'; it was humiliating, you would have loved it."
Katsuki slams his locker shut and crosses his arms, attempting to stare Kirishima down. Kirishima grins back at him, unaffected and disgustingly full of hope and optimism. Deku pretends he isn't paying attention even though he very clearly is from a couple of lockers away.
Fuck it. Katsuki's always been more of a direct kind of guy.
"Alright," Katsuki says, ignoring the way Kirishima perks up to spin in Deku's direction. "Deku, what do you think I need to work on?"
"Everything but the body," Deku replies immediately, before freezing as his mind catches up with his mouth. "I-I mean you're... y'know."
Deku's mouth moves uselessly as he tries to save himself, his hands gesturing towards Katsuki like some foregone conclusion.
"I'm what?" Katsuki taunts. "Go on, spit it out."
By now they've gathered an audience, everyone stopping to gather around to witness their fitness god give due vindication of Katsuki's superior physical being.
Katsuki grins triumphantly.
Deku scowls, squares himself up, and says, "Y'know, hot, but kind of a dick."
"Preach," someone calls from the next room over; it sounds like the round-faced one.
So Katsuki has learned two things from this - three, if you count the discovery that the hole between locker rooms still hasn't been fixed, which he doesn't.
The first is that Deku thinks he's hot.
The second is that Deku can be a bit of a dick himself when cornered.
Hot and kind of a dick apparently goes both ways. For maybe the first time in their continual existence with each other, they're in agreement about something.
Katsuki can work with this. It's not like he was getting anywhere ignoring it, anyway.
"With me," Katsuki says the next morning, waylaying Deku early enough that he hasn't even thought about lifting more than his toothbrush. "Your fucking weird little groupies can whip up their own endorphin frenzy this time."
Deku just squints at him uselessly, all sleep tousled hair and confusion.
Refreshingly, Katsuki doesn't even want to punch him for it. He has something else in mind.
"Get changed," he orders, giving Deku a shove to get him moving. "You're taking personal clients starting now."
Each step closer to the gym brings with it louder, more panicked muttering as Deku wakes up and realises where they're heading.
"I have cardio in ten minutes and Yaoyorozu-san wanted to work with heavier weights today," he says. "I was gonna spot for her; who's gonna spot for her? And Aoyama-kun needs constant supervision - he's gonna break something. Oh god, he's going to break himself."
"Who?" Katsuki says, swinging open the gym door. "Who cares, whatever. Kirishima's always there, right? Let him handle it."
"Kirishima-kun thinks 'let's get physical'' is the height of exercise music," Deku snorts derisively.
Katsuki can't even point out how massively rich that is, coming from Deku. Not with what he's about to do himself.
It took him all night to find a track that was Deku's kind of awful and his own kind of heavy just for this.
"This is actually pretty nice," Deku says, looking around at the spacious mix of equipment and matted floor space. "Why the hell weren't we using this?"
"Because if you bring a single extra dumbass in with you I'm gonna tie them in place of the punching bag," Katsuki says casually. "This is mine now, and it's invitation only."
Deku tests the thickness of the mats with a socked foot and rolls his eyes. "And I'm invited in because... ?"
Katsuki grins and hits play on the boombox he righteously liberated from the common room, nodding his head as the song kicks in.
"Smack my bitch up," it grunts, in amongst the sort of kick and drop Katsuki could get used to.
"Are you serious," Deku says, unamused by the way his face scrunches up. "You're such a dick; this is terrible."
Katsuki shrugs and starts his warm-up stretches. "I got things to work on, right? Figured you could help with that."
He takes advantage of the pause to work on loosening up his hamstrings. Deku stares at him as he does it, nodding to himself as if agreeing to something.
"No paying me until at least the third session," he says, pulling off his sweatshirt.
"You're in my gym, asshole," Katsuki says. "How about you pay me some time."
Deku just grins like he might, one day, and begins his own stretches into the ensuing quiet, broken only by the noise of the boombox.
Katsuki thinks yeah, it might not be so bad, having him around in his space and existence.
Just two hot people who are kind of dicks, improving themselves and all that.