Fair warning: Violence, abuse, blood. Just so you know.
Roxas fucks Axel, hard and relentless, pounding into him over and over again making the older Nobody scream and writhe beneath him. When the noise gets to be too much, Roxas backhands him—hard enough to hurt but not mark—and tells him to shut up. Axel complies as best he can, muffling his cries by biting his own hand, sometimes hard enough to draw blood.
When it's over, Roxas always takes the time to tell Axel what he thinks of him, whispering words like "whore" and "slut" and "really good fuck" into his ear, biting it, confident that the redhead's wild hair will cover the mark, just as his coat covers the scratches and bruises over the rest of his body. Axel only moans in response, wanting to wrap his arms around the smaller body above him but knowing that it will make the blond leave him, and he doesn't want that.
They've been in this "relationship"—if it can be called that—for several weeks. It started when Axel made a comment to the younger Nobody about his existence; how he was nothing and that he'd never get the answers he longed for. Roxas decked him, hitting hard enough to draw blood from the redhead's mouth. There was stillness for a moment, and then Axel leaned down and shoved their lips together roughly, smearing his blood on the blond's lips. Roxas made a muffled sound and shoved the taller man against the wall, dominating the other and the situation immediately, as he did from then on.
Now Roxas traces his fingers over the cuts and bruises on Axel's bare chest, delighting in the hisses of pain and sharp intakes of breath he can draw from the older Nobody by putting pressure on just the right spots. He bites the redhead's shoulder, then moves up to his ear, breath hot against it, slick with the scent of sweat and sex, and asks, "Why do you let me do this to you?"
There are a million answers to that question. The obvious ones are that Roxas is stronger than Axel and that Axel is a masochist. The one Axel wants to give him is less obvious: he wants to tell Roxas that it makes him feel alive to be hurt like that, and that the aches he carries with him later—the bruises that make him wince and the scratches that sting under leather—serve as a reminder that he's still alive. He thinks maybe he could be less dramatic and simply tell Roxas that the pain makes him feel, but he won't, because he knows that saying things like that could make the boy leave him. Roxas doesn't want to hear about feelings. Roxas doesn't believe in feeling. He only believes in truth and lies and touch, so Axel gives him another lie to believe in.
"'Cause you're the only one with enough balls to stand up to me," he teases, fondling the balls in question. Roxas fucks him again.