In the dark, Sean could be anyone. In the dark, from behind, with his shorts stuffed in his mouth as a sort of makeshift gag. These hips could be anyone's, this ass around Bill's cock. There's no now-familiar accent to those muffled grunts. Bill likes fucking in the dark; this way he doesn't have to think about why he's picked up the same guy more nights in the last few months than he can count.
In the dark, anyone could be Bill. On the nights when Sean hangs about the club for hours, nursing a beer and watching the door with one eye, he doesn't bother scanning the crowd for someone with similar looks. If Bill never shows, Sean will take anyone who offers. If the lights are off, if his eyes are closed, it'll make no difference. It'll be Bill fucking him, even if it's just in his head.