Chapter Text
"Hey, Deku..."
Katsuki's voice is muffled by the pillow he's lying face-down on. Izuku tilts his head at him questioningly. He knows Katsuki can't actually see him make the gesture, but he can feel Izuku's general sense of exasperated "What now?" pulsing through the bond between their thoughts, so. Same difference.
Katsuki doesn't move from where he's sprawled unceremoniously on the bed. "What the fuck actually are you?"
Izuku frowns. "Haven't we had this conversation before?"
He thinks specifically of that time Katsuki died, and then came back to life, and then asked the exact same question. They've definitely had this conversation before.
Katsuki turns his head to look at Izuku, who's sitting cross-legged on the floor with a battered copy of Les Misérables in his lap. "You told me what you think you are," he says. "But never in that explanation was a concrete affirmation of what you actually are. So, what the fuck actually are you?"
Sighing, Izuku dog-ears the page he's on and reluctantly puts Victor Hugo to one side. "I don't know," he replies. Katsuki narrows his eyes, and Izuku splutters. "I don't know! Nobody handed me a guide book or anything. Why would I have any idea?"
"Are you really telling me you've never once thought to find out?"
Izuku blinks sheepishly and shakes his head. Katsuki stares at him in silence for a second. Izuku can practically taste the cynicism. Then he exhales slowly like he's dealing with a brainless toddler and pushes himself up from the bed and on to his feet in one smooth motion. His eyes retain their deadpan scepticism, but the tiny smirk tugging at the corners of his mouth betrays his playfulness. "I know what we're doing today," he says, and Izuku gives up on his peaceful morning plan of sitting on the floor and reading in silence.
Half an hour later, Izuku finds himself being dragged out of the comfort of his flat and manhandled towards the library to, quote unquote, "figure this the fuck out".
It's been a month and half since Shigaraki almost killed the two of them and Katsuki found out the truth about Izuku. They'd been on leave from work since then, wandering around and seeing the world, but about a week ago Izuku had been forced to admit that he was horrifically homesick, and Katsuki had begrudgingly agreed, and they'd come back home.
As much as he hates to admit it, the world has seemed an awful lot scarier since Shigaraki returned. Even with Katsuki constantly watching his back, it's like his anxiety meter has been dialled to 100, with every dark corner, every death, sending his heartbeat spiking. He's been cowering in his flat - Katsuki's words, not his - since they got back, pointedly avoiding other people and, indeed, doing anything. With that in mind, he knows this whole "Let's go do some research" thing is probably just a ploy to get him back out in the world, but honestly, it's working, so Izuku can't really complain, as much as he'd desperately like to just sit on his bed and curl up against Katsuki's side and block everything else out.
Still, he can't say this hasn't piqued his curiosity at least a little bit, and he does feel appropriately stupid for never trying to figure things out for himself before.
When they walk through the library doors and find themselves confronted with several walls of books, Izuku realises that this might be a bit grander of a task than he'd been imagining.
"Where do we even start?" he whispers.
Katsuki pulls him over to the mythology section. "Your thing is life, right? And nature and all that shit."
Izuku nods slowly. "So," Katsuki continues, "let's start with Gaia." He pulls a book on Greek mythology down from the shelf and collapses entirely ungracefully on a beanbag on the floor. He pats the space next to him absent-mindedly. Izuku sighs and rolls his eyes just to keep up appearances, but sits down next to Katsuki and leans against him. The relentless pulse of anxiety inside him quietens as their breathing syncs up and the faint bond that links them hums at the contact.
They look first at sun gods like Ra, Amaterasu, and Belenus, but beyond the basic principles of life and light, nothing really seems relevant to Izuku.
("Aw, Kacchan, am I really like the sun?"
"Shut up or I'll kick you."
"You love me really," Izuku grins, kissing Katsuki's cheek and then dissolving into giggles when Katsuki places his palm square on Izuku's face and pushes him away, blushing furiously.)
So they move to looking at Roman nature gods, Faunus and Lupercus and the Greek wolf festival Lykaia, and then to Germanic paganism and Norse mythology. It's all linked - nature and life-giving and shapeshifting and resurrection - but everything just seems... mythological. And Izuku knows, really, that his entire existence is kind of mythological, but these ancient stories of tricks and adultery and cannibalism are all things he's heard before and definitely nothing he's ever felt in the slightest relate to him.
But five coffees, eight books, and twelve ancient religions later, they find something. A book on ancient Chinese religion mentions Taoism, and then Katsuki nudges Izuku, who's very close to falling asleep, and reads aloud.
"'Legends of so-called immortals were widely accepted by the ancient Chinese. They can freely change their appearance, and they move very swiftly and fly through the air, sometimes using wings.'"
Izuku extracts his head from the crook of Katsuki's neck and leans forward to read for himself, mumbling the words under his breath as he reads them.
"'Immortals usually live in clean and pure places such as high mountains, they do not eat cereals,'" - he snorts at that - "'and they appear only to people who perform the proper religious practices or have the right kind of destiny.' Kacchan, this doesn't sound like me."
Katsuki rolls his eyes. "Obviously not that bit. Just keep reading."
Izuku raises his eyebrows, but continues. "'They are immune to heat and cold, untouched by the elements, and can fly, mounting upward with a fluttering motion. They dwell apart from the chaotic world of man, subsist on air and dew, are not anxious like ordinary people, and have the smooth skin and innocent faces of children.'" He trails off. Sure, he's anxious quite a lot of the time, and he would probably say he subsists on granola bars more than air and dew, but those are small details. This is sounding... well, it sounds an awful lot like how someone would describe him if they were trying to make him sound like some sort of mystical faerie creature.
He continues down the page, his eyes widening as he reads the next bit aloud.
"'There are five classes of immortals. Human Immortals continue to hunger and thirst and require clothing and shelter like a normal human, but do not suffer from aging or sickness. Ghost Immortals are people who cultivate too much yin energy and are likened to vampires because they drain the life essence of the living.'" That's like..."
"Shigaraki," Katsuki finishes. "See?"
"You're right," Izuku admits, but he frowns. "But I'm not Chinese. My predecessor wasn't Chinese. Why would I be a part of Chinese folklore?"
Katsuki shrugs. "Beats me. Maybe someone far back in your freaky magical lineage was from around there. Or just took a vacation and ended up getting worshipped."
"We'll probably never know," Izuku murmurs, his finger hovering over the book where it lies open in front of them. "Does it say anything else?"
Katsuki turns the page and reads the rest to Izuku.
"'The earliest artistic and textual evidence of xian transcendents dates from the fifth or fourth centuries BCE. They were depicted as avian and serpentine hybrids who could fly through the universe, typically either combinations of a bird's body and a human face, or a human with wings sprouting on their back.'"
"I definitely don't look like that," Izuku mumbles.
Katsuki narrows his eyes. "Have you ever tried?"
"No?" Izuku replies, confused. Then the penny drops and his eyes widen comically. He leaps up. "Why have I never thought of this before? Kacchan, what if I can have wings? I have to try this!"
Katsuki stands up more calmly, looking faintly amused. Distantly, Izuku knows it's because the tables have turned and now he's the one dragging Katsuki around, which is exactly what Katsuki's evil plan was all along, but he's so excited about the possibility of uncovering something new about himself that he can't even be mad about it.
The second they get back to their flat and the door shuts behind them, Izuku pauses, and Katsuki looks at him expectantly. "Small problem. I don't actually know what I'm doing. Normally when I shift it just... happens."
Katsuki chokes back a laugh. "How did you do it the first time?"
"It just happened! I was emotional and the next thing I knew I wasn't human anymore."
"Deku," Katsuki says like he's trying desperately to keep a straight face. "You're the most emotional person I know. You're emotional all the fucking time, it's like your default fucking state. You're gonna have to give me more than that."
Izuku groans. "I don't know! I just, I was really scared then. But sometimes when I'm really upset, or really happy, the same thing happens, at least when I'm not trying to control it. So it's just any extreme emotion?" He sounds more like he's asking a question than making a definitive statement.
"Any extreme emotion?" Katsuki asks, stepping closer to Izuku and looking at him like he's formulating a plan.
Izuku eyes him warily. "I think so."
"Okay," Katsuki says with a tiny smirk, and closes the distance between them, tilting Izuku's face towards his own with uncharacteristic gentleness and kissing him softly, purposefully. Izuku leans into him immediately, his thoughts dissolving somewhat pathetically into incoherence as Katsuki pours all his love - love - through their bond.
Then Katsuki nudges Izuku with his thoughts, and Izuku suddenly remembers he's supposed to be using this explosion of raw emotion for something. He reaches into the corner of his mind, finding the little switch hidden there with practised ease, hopes distantly that this will do what he wants it to do and not just turn him into something small and furry if not simply because he really wants to keep kissing Katsuki, and flicks it.
At first, he thinks nothing has changed, because he's still on two legs and he's still got his very human tongue in Katsuki's mouth, but when Katsuki pulls away and Izuku opens his eyes, a pair of wings, mottled green, brown and black like a green kingfisher, are wrapped protectively around the two of them. Izuku shifts them experimentally, and the feathers shine as they catch the light.
Wings. He has wings.
He grins at Katsuki, who lifts a hand slowly and meets Izuku's eyes. Izuku nods, and Katsuki rests a gentle hand on one of Izuku's wings. His breath catches at the contact and he flinches instinctively - it feels far more personal, intimate, than he was expecting, and he knows he wouldn't let just anyone touch them like this - and Katsuki moves his hand back apologetically, but Izuku takes his wrist and places it back where it was. Katsuki pauses for a moment to let Izuku get used to the feeling before he runs his hand up and down, his fingers curling through each individual feather, then lets it stray back up to rest on Izuku's neck.
"You know it doesn't matter to me what you are, right?" Katsuki murmurs.
"Of course."
"But, that being said," Katsuki continues, "this is pretty fucking cool."
Izuku gasps dramatically. "The Katsuki Bakugou thinks I'm cool."
"I think you're a lot of other things too," Katsuki says with a smirk.
Izuku gulps and goes bright red, and he opens his mouth obligingly when Katsuki kisses him again.