Yagyuu isn't really sure if they've always been there, or if they appeared one day, or faded into existence. But one day, Niou has wings, and suddenly Yagyuu can't remember Niou without them.
They're huge, that's the thing; even furled tightly closed, the ends of the leading feathers brush the ground when Niou slouches, and there's a slightly damaged look to the tips that presumably comes from being knocked against things regularly. Yagyuu's not sure how that happens, though; as far as he can tell, they mostly aren't tangible unless it's convenient. When Niou sits down, there's no complicated fuss necessary to accommodate his wings; they just sort of splay out and around and curl under the back of the seat, passing through the wood in a couple of places. It's fascinating, and makes no sense to Yagyuu. But then, Niou's never really made sense. Yagyuu supposes there's no reason why he ever should.
Yagyuu spends a few days just admiring them covertly whenever he sees Niou around school. He never sees Niou open them properly, but he suspects the wingspan is a good few metres in width. They look somewhat like swan wings, or the wings of angelic beings in western myths, hilarious though that image is to pair up with Niou in his scruffy trainers and wrinkled shirts. They're a slightly creamy off-white; bone, thinks Yagyuu. Niou pays them minimal attention - he clearly knows they're there, Yagyuu sees him use one wing to fan himself idly a few times - and as far as Yagyuu can tell, nobody else registers their existence.
He can't work out how to ask about them. So, in the end, he doesn't.
He and Niou are lounging around outside one lunchtime, under the trees. It's early summer, and the heat and humidity is making them both kind of sleepy. Niou is flat on his stomach, his wings half-open and his eyes half-shut. The conversation has wound down into drowsy silence; the light is filtering through the leaves above, making the white feathers look dappled with shades of grey. Yagyuu - without really thinking about it - reaches out and runs a finger down the leading edge of the nearest wing. The contact makes Niou shudder strangely before he starts into full wakefulness and stares at Yagyuu in obvious confusion. Yagyuu starts to apologise, but he barely gets a word out before Niou's lips are against his.
Kissing Niou is painful; it's fine at first, but his teeth are inhumanly sharp. It's like kissing a mouthful of broken glass, and Yagyuu's lips are swollen and bleeding by the time they pull apart. Yagyuu manages to sneak into the nurse's office to steal a surgical mask and fakes a mild cough to explain it.
It's not enough of a deterrent to stop him from kissing Niou a day later, or again that weekend in Niou's room, or so many times after that he loses count.
There's something about the sensation of Niou's wings brushing against Yagyuu's bare skin that completely undoes him; Niou teases him a little for his lack of stamina and exploits the knowledge mercilessly. Thankfully, when Yagyuu slides the fingers of one hand under some of Niou's feathers and strokes the prickly, tender points where quills merge into flesh, that does equally embarrassing things to Niou's self-control.
Yagyuu sleeps deeply when Niou's next to him, one arm and one wing draped across him as Niou snores gently into his neck. He feels more awake on the mornings after those nights, too, as if waking up with Niou is a jolt of caffeine in his system.
He is startled awake one night; sharp pain, blossoming in his throat. He pushes Niou away gently as he sits up and then sees: Niou's mouth is slick with scarlet, sought in the darkness and without waking intent behind it. Niou seems suitably embarrassed, and the bleeding stops in moments. There is only the faintest scar left, when Yagyuu wakes the next morning, and it is gone by lunchtime.
He spots the scar a few times after that, but the pain never wakes him again, and Yagyuu doesn't dare ask if Niou is awake, if he ever does it deliberately.
The closest they come to ever talking about it is after they have sex one day and Niou is absentmindedly kissing at Yagyuu's fingertips. He nips lightly at Yagyuu's middle finger in response to a teasing comment, and because Niou's teeth are vicious even a playful bite draws a little blood.
Yagyuu pulls his hand back reflexively. There's a smear of blood on Niou's lower lip, and Niou's eyes are wide in startlement at what he's just done. Yagyuu hesitates, then shakily lifts his fingers to Niou's mouth again. Niou stares at him, wide-eyed, and then takes Yagyuu's hand in both of his as he licks gently at the wound he's caused. His wings spread and curl around and down, surrounding them both in a protective curl of soft whiteness, and Yagyuu's eyes drift gently shut as bliss overtakes him.
Months pass like this, and somehow it feels like everything and nothing is the same as it was; Yagyuu aces his exams and Niou does adequately on his, and Yukimura plots another reparatory victory for the team at Nationals. Yagyuu avoids touching Niou's wings in public, and Niou continues to act as though they don't really exist.
And then, one day, Niou is gone. Another boy sits at his desk; his shoe locker belongs to a boy from Yukimura's class; his parents believe themselves to have only produced two children. A dull and placid boy has a spot on the tennis team; he is an excellent technical player but that is his only virtue. Yanagi mutters soft noises about wishing for someone less predictable, and Yagyuu's chest tightens at the irony.
It's pointless to dwell on comparisons. Yagyuu practises his apparently-infamous switch with Marui, and tries not to mourn a boy that nobody else recalls.
Yagyuu allows himself a private moment, every morning, to check his neck and recall sly comments, warm hands and cool feathers and hot damp breath against his shoulder. Outside that moment, he makes himself forget. He moves on, in several ways. A soft-spoken boy from the baseball club confesses shyly to him one afternoon, and that leads to a few months of fumbling and of promises of forever that Yagyuu almost means. In the end, the boy breaks it off, apparently more scared of discovery than of being without Yagyuu after all. It stings, at the time.
The team wins Nationals this time, and Yagyuu finds a feather in his locker at the first practise after their victory. He sleeps with it under his pillow that night, and wakes to find it gone. He feels more refreshed than he's felt since Niou ceased to exist, however.
The next feather appears in his desk a few days later, and this one is stained red around the end, where the quill appears to have been snapped.
Yagyuu presses it against his face, that evening, as he indulges himself with memories of Niou that he supposes are more like fantasies now. He inhales the dusty scent that always clung to Niou's feathers even immediately after a shower, and brings himself to a stuttering climax that whites out his vision for a moment. He sleeps in boneless exhaustion afterwards, and is unsurprised that this feather, too, is gone by morning.
The third feather appears on his bed, red as sin, and thick with dark arterial blood that somehow doesn't mark Yagyuu's sheets even slightly. Yagyuu doesn't touch this one. Instead he spends the night sitting on his bed with his knees clutched to his chest, watching it carefully. Alas, he dozes just a little at some point around dawn; when he snaps himself back to alertness, the feather is gone.
His grades suffer a little in the next few weeks; his teachers scold him for inattentiveness. It's alarming. He's been spending too much time anticipating the next feather, the next sign. He reprimands himself, and doesn't even allow himself to check his neck in mirrors for a solid week.
And then he sees Niou when he's out with his parents in Tokyo one Sunday, across a crowd of people in a mall. No wings, but it's definitely Niou in every other way; the hair, the wrinkled clothes, the sly grin. Niou winks at him, and then ducks out of view, and Yagyuu fights his way through the crowd as politely as desperation will allow. Niou's nowhere to be found, of course.
Feathers start turning up on Yagyuu's bed every day, piles of them, unbloodied and smelling of dust. Yagyuu loses track of how many there are or if the old ones are vanishing as the new ones appear; he sleeps on small drifts of prickly quills and soft down and hopes desperately that it means something, something good, anything as long as it's soon.
And then he wakes up one night to find his nest of feathers gone. Instead, there's an arm draped across him. Hot moist breath rasps against his neck, and then Niou bites him gently - teasingly, even - with teeth that feel even more ragged than before.
I missed you, Yagyuu says into the darkness, and Niou laughs.
It hurts when Niou kisses him, and the scars on his neck are still swollen and inflamed the next morning, but Yagyuu doesn't care. He doesn't even care that Niou's phone goes off early, that Niou still somehow makes him absurdly late for school, that his mother pulls him aside to icily scold him for inviting his friends to stay over without asking.
He grins behind his surgical mask, and pulls his collar up high, and listens to Niou's tuneless whistling all the way to school in complete contentment.
He's going to miss the wings. But the rest of Niou is plenty enough to make up for the downsides, even so.