Sometimes, Axel hurts him. A tiny ball of fire no bigger than a marble—it doesn't look like it could do much damage. But hovering over him, it is terrifying. So close to his fragile skin, it makes him wince and sweat. It rolls lazily in the air, just above his stomach, flirting with the idea of dropping just the tiniest bit. It turns his blood into steam and he shudders. And Axel smiles and makes the fire go away. He leans in with a completely different but equally damaging fire to consume Demyx in a wonderfully terrible way. Because it was all a joke. It was a test, a tease, a game that Axel loves to play. But sometimes it hurts. Because sometimes Axel forgets. He forgets that it's just for fun, and he lets the flame lick Demyx, leaving scorch marks along his body. They hurt so much, and Axel just laughs and tells him to "suck it up." And he bites his lip, and tries to hold it in, because Axel could never understand how damaging the flames are, how they bite into his flesh and hurt.
It's not the only way Axel does it. It's not the worst way either. Demyx walks down the halls of the empty world they all share, alone with his thoughts. Then, in a moment, Axel is behind him, right behind him. Hey there, Waterboy. His breath is as hot as the rest of him, and it caresses Demyx's ear. I hear your veins are filled with ice. And then there's fire, a hot, hot, burning hot hand slipping inside his robe. Is that so? Maybe someone should warm you up a little, hmm? And Demyx turns around, but it's too late. It's always too late. Axel has already gone, vanished laughing into the darkness, leaving Demyx standing in the hall breathing hard.
Sometimes Axel hurts him. But it's all right, because sometimes Demyx hurts him back. When Axel is the way Demyx likes him best, his lanky form stretched out, taking up the full length of the bed, Demyx gets his revenge. Tiny drops of iced cold water that pelt the redhead's equally fragile body, quickly turning to steam and hissing into the atmosphere. And he gets to hear Axel scream for a change. Demyx always watches closely, enraptured. He's tried it on himself, trying to get a taste of the pain he can inflict, but it feels pleasant and soothing to him. But Axel tells him that they eat into him with a biting cold that burns through the very force of it. His idea of hell are those little drops of water slipping and hissing against his skin. Like Axel and his flames, Demyx can't understand how his element could do harm. It's so much a part of him, it doesn't bother him. It makes him smile to hurt Axel like that. It makes him feel like he understands Axel a little more.
They hurt each other, and not always with elements or touch. Their words are always perfectly sharpened and aimed, sometimes exchanged in anger, and sometimes just out of the prickling desire to see the other cringe. You're nothing to me, Axel sneers, you know that, right? You're nothing. And Demyx wants to cry, and he can feel tears stinging behind his eyes, but he refuses, he pretends to just shrug it off. Sure. I mean, I'm not him. I think it's sweet, how you care so much about him. Especially now that he abandoned you. And Axel stares at him, hurt obvious in his eyes. It's a low blow, very low, and Axel hates him for saying it, hates himself for being hurt by it, and hates himself again for having nothing low enough to sling back.
Axel and Demyx like to hurt each other, and neither really minds. It's all part of their game, of them being them. They like it. Because they aren't like other Nobodies. They're still empty inside, but it hurts. They miss them, the feelings. So they hurt each other, because it makes them feel. The pain bites, aches in their hollow souls, but they treasure it. Because it's something. It gives them something to feel, and reminds them that even if they don't have hearts, it doesn't mean they're totally dead inside. It's not love because, as far as they know, they can't love. But the pain is the most precious gift they can give each other. It reminds them of a life they once had, of things they were once capable of feeling.
Axel hurts Demyx, and Demyx hurts Axel. And it's all right, because it's the only way they can think of to remember that they care.