It's late. It's late and Oikawa still isn't back yet, and Iwaizumi grumbles to himself, flinging on a coat as he stumbles out of the house onto the sidewalk, rubbing his bloodshot eyes blearily. He spends almost every day studying until he can barely open his eyes. University, and all that.

The walk to school isn't very long, but it's cold, and his nose is red and burning with the sharp sting of a familiar cold. The gym lights are on, and he pauses outside of the door for a moment, listening to the sound of volleyballs hitting the ground with a solid smack, full of a raw power and a precision Iwaizumi can already visualize in his head.

He enters just as Oikawa is in the middle of a jump serve, his body arched and slick with sweat, glinting in the harsh artificial light of the gym, arm raised over his head as he sends the ball barreling over the net, slamming into the ground so hard the sound rings in his ears. Oikawa lands, and Iwaizumi doesn't miss the way his knees tremble and threaten to give way under him, or the telltale flicker of pain that vanishes as he straightens.

Iwaizumi can see the beginnings of the same old well-practiced smile form on his face, and it's horribly fake and just pisses Iwaizumi off because this idiot insists on hurting himself yet still pretends that everything is all right. Like hell.

"Stop it. Don't smile if you don't mean it, shittykawa." Iwaizumi storms over and grabs his collar, damp from exhaustion. "We're leaving."

Oikawa resists, digging his heels in and pouting like a 3-year-old, like he thinks it will work on Iwaizumi, not when they both know it won't.

"Aww, Iwa-chan, you didn't have to come all the way out here just to get me! I can walk home by myself just fine!" Oikawa leans in until their noses are inches apart, and Iwaizumi can feel his breath ghosting across his lips. His hand is still wrapped around Oikawa's shirt, around his neck, and he dimly realizes how easy it would be to pull him down and close the distance between them. "Or are you worried that someone might try to kidnap me, because I'm just so beautiful and charming and irresistible?"

The familiar rhythm of their banter snaps Iwaizumi out of… whatever-it-is, and he is appalled at himself. What the hell just happened? What was he thinking? He's pretty sure his whole face is red right now, heating up like a toaster as he inwardly panics. Hopefully Oikawa will just think he's flushing from anger, not embarrassment.

"Shittykawa! Trashykawa! Like anyone would want to kidnap you!" Iwaizumi flings Oikawa away, watches as he stumbles back laughing, cooling sweat falling from his temples and glittering like diamonds on the floor. Even disheveled and overworked, Oikawa's hair is perfect as usual, wavy and styled and sleek. Iwaizumi growls. Some people get all the luck.

"Come on, let's go." Iwaizumi walks off, switching the lights off behind him, knowing Oikawa will follow. Sure enough, he skips ahead, like he hasn't been grinding on the court for more than five hours, like Iwaizumi doesn't have to drag his ass out every night.

He watches Oikawa out of the corner of his eye, the way his eyes shine in the streetlight, lighting up when he talks about volleyball and aliens, because Oikawa talks all the time, about everything and anything, and-

"Iwa-chan! Are you even listening to me?"

Iwaizumi blinks, trying to recall what Oikawa has been saying and fails terribly.

"I wasn't – "

And then Iwaizumi's reflexes kick in and he grabs Oikawa's arm, hauling him back up to his feet, preventing Oikawa from falling as his knees buckle, unable to hold up his weight.

"Idiot! You know your knee is injured already, overworking yourself is only going to make it worse!" Iwaizumi barks, acute fear spiking through him and making his voice sharp. He shakes Oikawa's arm maybe a little too roughly, worry bleeding into his voice as he says, softer, "No more staying back late."

Oikawa's eyes are wide with shock and pain and some other emotion Iwaizumi can't quite identify, but he grimaces and looks away.

"I mean it." Iwaizumi grinds out.

"Iwa-chan! I always knew you cared about me!" Oikawa's false smile is plastered to his face, voice ringing with a hollow cheerfulness that neither feels, echoing loudly in the dark silence. "After all, you love me the best!"

"I'm serious, Oikawa." Frustration bubbles to the surface and his fist clenches involuntarily around Oikawa's arm. "This is serious. You could end up really hurting yourself."

Oikawa avoids his eyes and tries to shrug it off with a forced nonchalance. He doesn't want to admit defeat, Iwaizumi thinks, because he blames it on himself, every time, for every loss. And this match against Karasuno was especially bad, because Kageyama was there to rub it in his face.

"You worry too much. I'll be fine." And there's a coldness there that wasn't quite there before, a stiff finality fenced around his words that Iwaizumi doesn't like.

And once again Iwaizumi is overwhelmed by helplessness and frustration, because he just wants to make this idiot see, and while he doesn't know how to deal with helplessness, he knows how to deal with rage. Rage is good. Anger is good. He knows how to handle that.

"You're being an idiot!" Iwaizumi smacks him on the head, ruffling his perfect brown curls. He pulls on Oikawa's arm, this time being the one who brings their faces close together, watches his brown eyes widen in surprise and a guarded anger. "You are hurting yourself. Overworking yourself isn't going to help the team any. We lost. Deal with it."

Years of practically living with Oikawa has seasoned him in the nuances of his facial features, his quirks, and now he can tell that Oikawa is hurting, both emotionally and physically, faced with a truth he doesn't want to admit. And when that happens, he lashes out. Oikawa likes to find the little chinks in people's proverbial armor and use words to attack them ruthlessly. Oikawa likes watching people break, likes breaking them. That's just the way he is, and Iwaizumi knows it.

So when his lips twist into an expression of carefully constructed scorn and disgust, when his eyes narrow into slits and his chin lifts up high, using his height as an advantage to stare down at Iwaizumi, he tries not to let it get to him. He tries not to let it hurt when Oikawa spits out, "At least some of us try, Iwa-chan. Some of us care about volleyball and winning and losing and try to get better through practice. Not that you would know."

He tries to tell himself that Oikawa doesn't mean it and he's just exhausted and overworked and probably not thinking straight, would never say such things otherwise. He tries, and tries and tries, but it feels like his vision is tunneling and all he can see is Oikawa's scorn and loathing. Pent up frustration and exhaustion from staring too long at too many textbooks are making his vision blurry and there's a strange feeling in his gut, wrenching and painful and hard.

"And here I thought best friends are supposed to help each other, to support each other, but you've done nothing but get in my way!" Oikawa is almost shouting now, and Iwaizumi lets go of his arm and steps back. "What kind of friend are you? I wish you would just stop."

It feels like something snaps, then. Something is irrevocably and irreparably broken. Maybe it's Iwaizumi's self-control. Or maybe it's their trust. Whatever it is, his default emotion – anger – comes rising up like a great tide of unspoken words, fueled by hurt and frustration and worry. There is a tightness in his throat, and when he speaks, it comes out all raspy and clipped, tension strung taut between each word.

"Fine. You know what? Fine. Have it your way. Go back to the gym and practice or whatever. I'm not gonna stop you, so go ahead and you work yourself to death. Because I don't care anymore."

And then there's simply no good way to end this, so Iwaizumi turns and walks away, but not fast enough to miss the look on Oikawa's face. Before his face twisted into a blank mask of aloofness, for just a moment, Oikawa looked absolutely gutted.