Avengers AU -> Junkies
A bunch of junkies shares den and fantasy: they are superheros. At the beginning is just a game, a way to scape from their awful reality. But the edges between reality and fantasy start to fade till they aren’t able to tell which is which.
One night, under a drug induced delusion they decide go after the one they think is their archenemy, the cause of all their misfortunes and kill him. Loki the God of Mischief, who actually is Luke, their drug dealer.