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Izuku doesn't drink on school nights. So when his friends invite him to dinner, he sticks to water. Kacchan never drinks, complaining about the lack of nutritional value. So he's sober, too. And yet, the next morning, they're in bed. Naked.
Together.
He remembers everything like it's a movie. As he sits in Kacchan's arms, feeling the warm breath tickling his nape, Izuku tried to figure out HOW this happened. Because yes, Kacchan looks amazing that night. Smells like the cologne Izuku picks out for him last month.
But this?
Why would Kacchan kiss me? he thinks, embarrassed how many times this one moment plays through his mind.
But no matter how many times he slows it down and flips it over in his head, Izuku can't figure out why Katsuki pins him against the hallway outside his apartment and... The memory of their lips pressing together makes his hand come up, brushing over the buzzing skin. But were there signs before that Izuku missed? Maybe Kacchan's coy look over the table at dinner. How Kacchan's voice teases Izuku about 'catching up to him' in the ranks.
They leave together that night, which isn't exactly strange. Kacchan always drives Izuku! That's normal. But the way his hand fits perfectly on Izuku's thigh is something new. Something that makes his heart race, even as he parts his legs a bit to give Kacchan more palm space. When they stop at the light, something compels him to glance over. Kacchan's so pretty under the streetlights, one hand casually resting on the wheel. The other is still on his thigh, thumb brushing the inner seam like it lives there normally.
Izuku's stomach is butterflies.
"Kacchan?" he calls softly, though it sounds like it's coming through the speaker from how loud it is.
Red eyes sway with the ease of a cat awakening from an afternoon nap. Still, the moment their eyes meet, something like static rushes through Izuku.
Something's... different.
And then they're walking up to his apartment with an undercurrent that Izuku doesn't know how to place. It almost feels like Danger Sense is back, except he doesn't want to escape. If Black Whip was still here, he's scared it would wrap around Kacchan and pull him against Izuku. Though it's that distracting thought that makes him struggle with his keys, laughing with a tension that only grows when feeling Kacchan's heat against his spine. Then, there's a hand on his waist. He's flipped around, back slammed against the wall.
Kacchan tastes like home.
His cheeks go red when the next memory blooms. Izuku isn't exactly innocent, but the way Kacchan lifts him off his feet and carries him into the apartment is something downright criminal. And then the night gets... intense. Their sex is intimate, earth-shattering, full of love-
Love?! Izuku looks down at the arm around his waist, traces the scars on Kacchan's skin to try and calm his racing heart. I mean, of course I love Kacchan. I've always loved him, he's my favorite person.
He just didn't know his love would show itself like this. And Kacchan-
"Ugh." The man of the hour stirs behind him, and Izuku goes ramrod stiff when a warm nose buries into his collarbone. "Your bed sucks, Freckles."
"So-Sorry," he whispers, unsure how he's supposed to process this. Especially when Kacchan tugs him closer and huffs against his ear.
"How long have you been up?" Kacchan asks, like there's nothing weird being naked and pressed together. If Izuku moves an inch, he can feel JUST how okay the pro-hero is with the situation.
That was inside me?! he thinks, unsure how he feels so good after taking Kacchan.
Without permission, he's hit with a flash of last night's memory. Kacchan, sweaty and flushed, grinning while their bodies start another round. That look of fondness during their third (or fourth? He can't remember) round feels seared forever over Izuku's swelling heart.
"Oi." A tug on his cheek makes him whine, following the pull so he can drop back onto the bed. Kacchan lets go of the freckles, and Izuku hates that he frowns when the man slips out from the sheets.
"Um, Kacchan..." But when Kacchan looks at him, Izuku doesn't know what to say.
He tries to find a good way to ask while he gets ready for work. Kacchan doesn't have patrol today, so he's fine with stealing some of Izuku's clothes and heading to the bathroom. When he hears the shower going, Izuku freezes. Is he supposed to... join? Ignore it? Make a joke?
"He didn't ask you to join," Izuku mumbles. But Kacchan will have a hard time getting the scratches Izuku left on his back-
Face hot, Izuku rushes to the kitchen. He should be a good host and feed his...
"Friend." he says outloud on purpose. "We're still friends... Right?"
And that's all he's ever wanted in life. To be someone that Kacchan looks at as someone that matters. And he sure did last night, when he was helping Izuku straddle his hips and ride-
He's never going to make it through work like this. How can he teach with Kacchan on his mind?!
When Kacchan emerges from the bathroom, he acts like they didn't just have the craziest night of their lives. He picks on Izuku's lack of seasoning, hip-checking him to 'get unstinky' while he finishes their breakfast. Izuku's heart aches with how domestic this all feels. He scrubs every inch of Kacchan off his skin. Well, the parts he can. But Kacchan treats sex like a battle, and makes sure he leaves his mark.
Like the open bites on Izuku's ass from when he ate him out, or the hickey peeking out from the edge of his shirt's folded collar.
"Oh no..." He tries to tug up the fabric, but it's a lighthouse in the middle of a storm. Izuku knows his kids (and some of his fellow teachers) will ask.
But when he sits down to eat a quick breakfast, a glance over the table ends up turning his brain into a big bowl of mush. Because Kacchan's looking at the purple peeking from Izuku's collar with more pride than when he defeated All For One. It's enough to make him forget how to eat his breakfast, and he loses some time to more memories of last night.
Things he still doesn't know he CAN think of. The touches, the groans. Kacchan's mouth pressing soft kisses on his wrist while bringing Izuku enough pleasure to make him cry. And Izuku isn't exactly passive in their time together; he knows intimate parts of Kacchan from his tongue alone.
Izuku squeezes his thighs together.
"Alright, let's go." Kacchan tosses the dishes in the sink, ignoring Izuku's protest when he pushes him toward the bathroom. "Brush your teeth and hurry up."
"But the plates-"
"I'll wash them after I drop you off." And what is Izuku supposed to do with THAT domestic image?!
He snags his backpack and forgets his jacket. Katsuki snorts at his loose tie before stepping closer in the elevator, fixing it.
"God, you're such a mess," Kacchan mumbles, and Izuku feels the insane desire to pop up on his toes and kiss his soft smile.
But he's... scared. So he bites his lip and keeps to himself, scurrying into Kacchan's passenger seat. He sees how people stop to look at the car as they drive past, using them as a distraction. It's either that, or ask Kacchan the big question that could ruin them.
What does any of this mean?
Once Kacchan pulls up to the front of the school, Izuku rushes for the door handle. "Ah, thanks for the ride. Have a good day!"
"Oi." Of course he doesn't get away that easily. Slowly, Izuku turns back, waiting for Kacchan to clear the air. To say it 'meant nothing', to forget- "Don't mosey around after school," Kacchan says, making him blink. "If you make me wait cause of Squirt Gun's dumb ass-"
"You're..." Izuku swallows. "You're picking me up after?"
"Duh." And Kacchan... blushes. Just a dusting on his ears, but still. "I'm not a shitty boyfriend."
Izuku almost falls out of the seat. Boyfriend? When did THAT happen? He was sure Kacchan was going to forbid him from even think about it, and now...
"Right." Izuku nods. "I'm Kacchan's... boyfriend."
Kacchan scoffs. "That's right. You're mine, and everyone's gonna know it."
All the nerves and anxiety from the morning vanishes in the claim, Izuku leaning toward Kacchan as he smiles. "I'd... I'd like that."
"Good. Cause I'm taking you out on a REAL date after work." He talks so big, but now that he's looking, Izuku sees Kacchan's nerves flaring up.
So he nods quickly, hand reaching out to grab at the shirt Kacchan borrows. He pretends not to notice how tight it is on the other's bigger chest. "Um, so then... I should kiss you before I go, right?"
"Whatever." Except Kacchan's leaning in even as he pretends not to care.
The kiss they share outside of UA isn't like last night. There's no fire, no need to trace every inch of Kacchan's mouth. But Izuku thinks it's cause this one... he knows this time won't be their last.
Because Izuku will get to kiss his Kacchan for the rest of their lives.