Work Text:
Izuku notices it in the quiet spaces first.
Katsuki has always been loud; explosions in his laugh, in his footsteps, in the way he exists in a room like it’s daring him to leave a mark on it. Even in their mid-twenties, even as a top-ranking pro hero who knows how to hold a press conference without blowing something up, Katsuki still crackles with energy.
So when the apartment is quiet, too quiet, Izuku feels it like a wrong note.
It’s nearly ten at night. Izuku’s grading papers at the kitchen table, glasses slipping down his nose, red pen paused mid-comment. Katsuki should have been home an hour ago. There’d been a text, "late, patrol ran long," which is normal.
What isn’t normal is the absence of noise when the door finally opens. No muttered curses. No heavy boots kicked off with unnecessary force. No explosion of presence.
Izuku looks up just as Katsuki steps inside. He still looks like himself at first glance; broad shoulders straining against his hero jacket, ash-blond hair tied back messily, face sharp and familiar in a way that makes Izuku’s chest warm even after all these years. But then Katsuki shrugs out of his jacket a little too slowly, movements stiff, jaw clenched like he’s biting back something unpleasant.
Izuku’s pen is down before he realizes it. “Kacchan?” he says, standing.
Katsuki freezes for half a second. Just half. Izuku almost misses it—but he doesn’t. He never does. “I’m fine,” Katsuki says immediately, too fast, not looking at him. “Don’t get up.”
That’s strike one.
Izuku moves anyway, padding across the floor, already cataloging details. Katsuki’s skin has a faint sheen to it—not sweat from exertion, but the dull gloss of fever. His eyes are a little unfocused, pupils blown wider than usual. When Izuku gets closer, there’s heat rolling off him, sharp and unmistakable.
Strike two.
“Kacchan,” Izuku says again, softer this time, reaching out.
Katsuki steps back. “Don’t get too close.”
The words are sharp, barked out like an order, but there’s something under them that makes Izuku’s chest tighten. Not anger. Not irritation.
Fear.
Izuku stops, hands hovering uselessly in the air. “…You’re sick,” he says quietly.
Katsuki scoffs, but it comes out rough, edged with something wet that turns suspiciously into a cough he tries and fails to swallow down. “It’s nothing,” Katsuki snaps. “Just tired.”
Strike three. They’re out.
Izuku exhales slowly, grounding himself the way he teaches his first-years to. Katsuki hates being sick. Hates the loss of control, the vulnerability, the way his body betrays him when he needs it most. Even after marriage, after years of shared beds and shared scars, this is still one of Katsuki’s walls. Izuku steps back—not away, just enough to give Katsuki space. “Okay,” he says. “Then go shower. I’ll finish grading.”
Katsuki squints at him, suspicious. “…That’s it?”
Izuku smiles, small and non-threatening. “That’s it.”
Katsuki grunts, clearly unconvinced, but trudges toward the bathroom. His steps are heavier than usual, uneven. Izuku listens to the shower start, waits exactly thirty seconds, then quietly moves. He sets water to boil. Pulls miso paste from the fridge. Ginger. Honey. Katsuki’s favorite mug; the stupid one shaped like a grenade, chipped at the handle. He lays out clean clothes on the bed, the soft ones Katsuki pretends not to prefer. By the time the shower turns off, the apartment smells warm and grounding. Katsuki emerges wrapped in steam, hair damp and curling at the ends, skin flushed pink in a way that makes Izuku ache. He looks… smaller, somehow. Not weaker but less armored.
Izuku approaches carefully, holding the mug out like a peace offering. “Tea,” he says. “Drink it.”
Katsuki scowls. “I said don’t—”
Izuku reaches out and presses the back of his fingers gently to Katsuki’s wrist.
He’s burning up.
Katsuki sucks in a sharp breath, tension spiking—but he doesn’t pull away. His shoulders sag, just a fraction. “…Damn it,” he mutters.
Izuku’s voice stays steady. “You’re running a fever.”
“Tch. I’ll sleep it off.”
“Not without fluids. And food. And rest.” Izuku meets his eyes. “And me.”
For a long moment, Katsuki looks like he might argue. His jaw tightens, teeth grinding, pride warring with exhaustion. Then he exhales, sharp and defeated. “…Don’t get sick,” he says gruffly. “You’ve got classes.”
Izuku’s heart stutters.
That’s what this is about.
He steps closer now, slow and deliberate, and this time Katsuki doesn’t move away. Izuku cups his face, thumbs brushing over warm skin, feeling the faint tremor beneath. “I’ll be fine,” Izuku says softly. “I’ve dealt with worse than a cold. Remember?”
Katsuki snorts weakly. “Show-off.”
Izuku smiles and presses a kiss to Katsuki’s forehead. He lingers just long enough to feel the heat, the trust.
They settle into bed together—Katsuki half-sitting, stubborn even now, Izuku tucked against his side. Katsuki drinks the tea with a scowl, complains about the taste, but drains the mug anyway. Izuku feeds him soup one spoonful at a time until Katsuki grumbles himself into compliance.
By the time Katsuki finally sags against him, breath evening out, the fight gone, Izuku’s arm is numb and his heart is painfully full.
Katsuki’s voice is hoarse when he murmurs, barely awake, “You didn’t listen.”
Izuku smiles into his hair, fingers combing gently through damp strands. “I never do,” he says quietly. “Not when it comes to you.”
Katsuki hums, a low, content sound, and finally lets himself rest.
Izuku stays awake long after, watching the rise and fall of Katsuki’s chest, memorizing the warmth, the weight, the privilege of being close.
Tomorrow, there will be medicine and sick leave and grumbling texts to the agency. Tomorrow, Katsuki will pretend he wasn’t scared.
But tonight, Izuku is here.
And that’s enough.