Karkat opens the door to the apartment and lets John in without saying anything, which is how John likes it, anyway. John wouldn't hit him if he talked or anything – he's not a beast – but there's nothing to say anymore.
Karkat undresses with his eyes cast to the floor, and John doesn't watch him for more than a second. There's nothing attractive or interesting or right about a male body, about watching one undress in front of him, even if it is a troll. It's just flesh, made of dust.
Karkat crawls onto the bed, lies on his stomach, face pressed into the bedsheets, legs spread, hands resting on the sheets next to his ears. The light falls onto him in a way that makes his skin look rippled, like scales. Trolls used to have scales in their post-cocoon form, long ago, he hears. The thought creeps him out. John imagines that like this, on his belly, Karkat could slither up the bed, up the wall. It turns his stomach.
"Turn over," he says, and Karkat looks back at him with shock in his expression, so John says, "You're creeping me out like that."
Karkat turns over, and John unzips. Pushes down his jeans and his underwear enough to bare himself. He's half-hard, about normal for this part, so he thinks about breasts and slick feminine wetnesses until he's up all the way, and then he kneels on the bed, between Karkat's spread legs, leans down. Uses his hand to guide himself into Karkat, who's slick enough to go on though not the way he likes it. Karkat's knees rise to frame his ribs, heels digging into his back; he feels trapped, but he wouldn't be able to get as deep in if he forced them down.
Karkat shudders, nook clenching around him. It feels good, and suddenly slick, and John presses deeper, into the heat, grunting with the force of his own movements. The knees on his ribs grow tighter, maybe enough to bruise, so he pushes one away with his hand, and ignores the whimper that comes from beneath him. Trolls are hard to damage.
He closes his eyes and imagines breasts and curves, long hair and clear gentle eyes. The soft wet around him helps push away the thought of what's really there.
After a time, the body beneath his starts rising to meet him, clenching around him. He doesn't mind. It feels good, the depth and pressure and the slick slide in and out.
He comes not long after that, deep inside, and pulls out before things can get messy. Uses the bedsheet to wipe pink juices off himself, not wanting his clothing or his skin to stain with it, and pulls his jeans back up, rebuckles his belt. The body on the bed is just lying there, feet flat on the mattress, knees in the air, legs still open as if in invitation.
There's red on the sheets, and slick whitish fluid, his own, slipping out of the hole.
John turns away. "At least cover yourself up so no one sees you when I open the door," he says. The sheet moves, covers the mess.
"Same time next week?" John checks.
A rustling from the sheets. "Yeah."
He shuts the door behind himself. The winter air in the hall is cold, making him shiver.