it takes place during the half-blood prince it starts and deviates at/from the seen where harry finds Draco crying in the bathroom (I think) but anywho they end up building this secret relationship, at first its just sex but slowly turns into something more. harry find's out that Voldemort had cursed Draco's arm and if he doesn't kill Dumbledore the he'll die. he's only got a tell like the end of the year or something. in the end he doesn't kill him and harry end's up cutting Draco's arm off at the last second to tray and save him.
If anyone knows what I'm talking about PLEASE PLEASE PLEAS tell me I've been going crazy looking for this thing and I'd really appreciate it.