400 pages into tgcf and the first au my brain came up with was high school teacher!xl and his student!hc, and hc's the only kid who likes his subject and does homework. hc looks at him like 'i'll fuck you on this very table' all the time, and xl's just ^____^ good boy.

but then xl get fired because he didn't let some rich shit beat up another kid, and the rich shit's father Spoke To Someone. so, xl leaves.
hc loses track of him. but then he gets into university and guess who teaches another boring subject there.

so when xl sees him for the first time, he doesn't recognise hc at first, because kid's grown up and sparkling now. but when he does, when hc sits on his desk, smiling, he thinks, ah, aren't you the kid who looked at me like 'i will fuck you on this very table.'

they fuck on xl's desk among all the students' papers and whatnot, yes.