Work Text:
In retrospect, it's incomprehensible to Bakugou why exactly he thought biting Kirishima in the cheek would bring his focus back around.
They're two days out from an important bunch of exams and, sure, after being cooped up inside to study for a week straight, Bakugou can acknowledge it's getting hard to concentrate on anything, much less the boring-ass mock exams Aizawa handed out yesterday. That doesn't mean it doesn't grind his fucking gears when Kirishima slips further and further into that far-away look that guarantees he's not paying a lick of attention to the crash course in Hero Law Bakugou is giving him.
So Bakugou bites him.
Not very hard, and not very long either. He just... snaps his pencil into two in his hand, growls, "Rocks for Brains, I swear to fuck—"
And leans in to pinch Kirishima's cheek with his teeth. Somewhat careful to not dig his sharp canines in too much, but enough to make a point. It does succeed in something, namely snapping Kirishima out of it with a startled "Bro?!" as he shoots upright in the beanbag Bakugou graciously lets him use when he's in his room. "Did you just— Ow? Hello?"
Then some of what happened seems to register, because Kirishima blushes bright. Fucking. Red.
"Oh shut up", Bakugou hisses back, refusing to acknowledge the warmth blooming on his own cheeks. "Are ya gonna listen now or what?!"
(Seriously, what's the big deal? Between exploding Kirishima and biting him, the intention is the same. It's that idiot's fault for drifting off in the first place!)
Kirishima is still staring at him, still flustered, "I mean", rubbing his palm over the faint indents Bakugou's teeth left on his skin. "Uh... huh? I guess? Damn, you got quite the bite, man."
That does not flatter Bakugou. No way. Even if it's coming from a guy with chompers like a Great White, just... Jaws-levels of big and dangerous. Not at all badass, nu-uh.
A huff of "Whatever!" cuts through both Bakugou's train of thought and the puzzled head-tilt Kirishima is giving him. "Section Two: International Conflicts and Heroic Intervention. Go."
Kirishima breathes a long-suffering groan. "Sir, yes, sir..."
When they get their grades back, Kirishima tackle-hugs Bakugou right there in the middle of the hallway — "I got a B! A B, Kats! I'm gonna cry. Thank you, you freaking genius!" — and Bakugou yells at that selfless fool to take credit for his own achievement, or face his wrath.
That's how it starts.
*
Once biting has been proven to be an effective tool, Bakugou uses it — liberally.
To get Kirishima's head out of the clouds like that first time; as a silent Stop it when Bakugou is tired as hell and Kirishima isn't letting him drift off to sleep; during their sparring sessions; just because. Kirishima's cheek is his favorite target, but his shoulder is fine too, or his hands when they're in biting range. Like with the explosions, Kirishima seems to quickly accept it's an occupational hazard of being Bakugou's best friend, and laughs every time he does it.
Equally as quickly, they find out that Kirishima's quirk doesn't mix well with this new habit of theirs. Bakugou's jaw hurts for hours that one time Kirishima guards against it. Bakugou doesn't say anything about it, afterwards. He snuck up on him after all; it's pretty sick that Kirishima's instincts kicked in that fast.
But Kirishima never does it again, and in return, Bakugou somewhat softens his bites.
1-A is entirely unfazed by the sometimes more, sometimes less friendly biting commonly happening between two of their classmates. Bakugou figures that says something about them, not that he cares what they think. Even the squad merely takes note of that added element to their rough-housing with a deadpan, "That checks out, yeah", voiced by Sero.
Bakugou, currently chasing Kirishima around with a snarl for burning something as simple as pancakes, flips him off. With both hands.
Never let it be said Bakugou Katsuki can't multitask, fuckers.
Then comes 1-A's bi-weekly movie night. Some shitty biopic is on, about this dude and his dog. Bakugou had a long fucking week, in his mind he's got both feet in bed already, and fine, perhaps that makes him a bit cranky. It's whatever.
Until Kirishima elbows his side, whispering, "Dude, stop fidgeting!"
Bakugou kicks him under the blanket they share. Kirishima huffs—
—and bites his shoulder.
For one motionless instant, Bakugou freezes up. Big, dangerous, badass Great White chompers, remember? Then a slight, stinging pain sinks in and he's muttering, "Oi, the fuck, Kiri?" before he can think twice about it.
Kirishima lets him go with an incredibly obvious gasp, given the dark room with only a quiet, melodramatic movie to cover it. "Oh man. You okay, bro? I'm so—"
"You good?", asks Jirou next to them, a thin eyebrow raised as her gaze flickers away from the man breaking down on-screen.
"Fine", Bakugou tells her as well as Kirishima, pulling his top aside to glance at the neat half-circle of pinprick-like, red dots now adorning his shoulder.
Shrugging, Jirou turns back to the TV. Kirishima, on the other hand, looks about as sad and lost as the dog howling in the rain. Bakugou sighs.
"It's fine, don't make me repeat myself. Just didn't expect it."
"But—"
"Eijirou. Does it look like I'm dying or some shit? Shut up and watch the dumb dog."
Wide awake again, Bakugou spends the rest of movie night semi-aggressively leaning into Kirishima's bulk with the same shoulder he bit, a wordless show of how minimal the damage done really is.
So that becomes a thing, too.
Not as often or as gratuitous as Bakugou's biting catalogue of meanings, but a thing nonetheless. Kirishima is ridiculously gentle with it, though. His bites are barely more than a brush of pointy teeth over skin. A silent request for attention here, physical emphasis for Bakugou to settle down and behave there. Bakugou would rather burn people to cinders than let them touch him out of the blue any day, but Kirishima has been an exception to that rule for longer than Bakugou cares to track down or admit.
And, well. Kirishima listens up when Bakugou does it, so he owes him the same. Or something.
It's really not that deep, no matter how many times Kaminari bursts into giggles over it.
*
The winter months bring everyone together.
Specifically, the set of heated futon tables that appear overnight manage to draw everyone in from their cold, kotatsu-less rooms into the communal spaces. A swift overview of the situation reveals there's exactly one spot left. Coming in vaguely frozen from his weekend jog, Bakugou's eyes fall on that, then meet Kirishima's by the elevators — and they both make a run for it.
Look. Bakugou absolutely hates snuggling up to anyone. It's fucking icy outside, though, and if he can suck it up enough to design an entirely new Hero costume around countering those temperatures, then he can bend his principles a little here too.
Besides, it's Ashido on one side (who hugs him at will regardless, that pink menace) and shitty Deku on the other. Bakugou grew up with that dickhead; this isn't even remotely on the map of dumb bullshit they've managed to overcome.
Also, Bakugou is partial to a good kotatsu. Sue him.
Of course, since Kirishima is Kirishima and Bakugou is Bakugou, neither of them slows down a single bit in their mad dash for that perfect-warm chunk of Heaven on Earth. Predictably, they collide mere inches from their common goal. Spitting out curses, Bakugou sparks his palms at Kirishima while Kirishima shark-grins at him, unflinching. They wrestle, roll away a bit, crawl closer to get dragged back by the other.
Ashido keeps reading her manga and Deku keeps sipping his tea, their struggle drawing mild interest from the others at most.
"Get off me, Shitty Hair. Off! That spot is mine!"
"No can do, Bakubro! I'm gonna take a cozy nap under that kotatsu, and you cannot stop me!"
Beyond words, Bakugou grabs Kirishima by his shirt and slams him to the ground to go for his cheek.
Kirishima holds onto his shoulders and goes for Bakugou's cheek.
And yet again, they meet in the middle.
With their lips.
Technically, they knock their teeth together and as a consequence their lips touch, too. Technicalities don't matter much where Bakugou finds himself very suddenly kissing-slash-cutting-his-bottom-lip on his best friend's Jaws-worthy fucking shark teeth, holy fucking fuck.
They come apart with near-identical howls of pain, holding their mouths and blinking at each other through the resulting tears. "Oh boy", goes Ashido next to them. Deku is wise enough not to say fucking anything, highly aware he'd be next on Bakugou's list of people-to-murder.
After Kirishima fucking Eijirou, that is, who is going fire-engine-red in the face at an alarming rate.
"Shitty Ha— Fucking Rocks for B— Eijirou!!"
"Yeah, b-bro? I mean, uh, Katsuki...?"
"What do you mean 'Katsuki', you—"
Then it clicks. Their position. The staccato-beat of his heart against his ribs, wholly different to plain rage. Bakugou's lip gently dripping blood on Kirishima's shirt.
The kiss.
Oh shit.
They kissed.
Bakugou sits up a little, eyes wide as he wipes at his chin with the back of his hand. It comes away red. "You..."
Ashido's far more invested "Oh boy" is followed by Deku clearing his throat.
"Aaand that's our cue. Hey, Shouto, got some room for us? Cool! Nope, Mina, you're coming with me. Let's go."
They leave. Or maybe they don't. Bakugou's attention is kind of elsewhere.
Specifically on the part of his brain lighting up like Shibuya Crossing on New Year's Eve. And the realization that god-fucking-damnit, stupid Kaminari was right.
It is that deep.
"You..."
It goes through Kirishima too, Bakugou can practically time the instant his himbo-mind flips a switch from panic to... Eagerness? Hope? It's all in the glint to his eyes as he gets his elbows underneath himself, clumsily bringing himself that crucial bit closer.
"Me? Yeah?"
Bakugou also clues into the fact that he could squash all… this, whatever is in the air right now. Crush that hope and pray they'll be able to go back to how they were before (predating the biting, even).
But that's the last thing he wants, actually.
Like before, Bakugou grasps Kirishima's shirt, pulling instead of pushing. He licks his bottom lip and tastes iron.
Then he smirks, and Kirishima smiles in return.
"You gonna kiss me again, hah?"