Found: specific Gabriel/Sam AU
In it, angels were living on Earth but Sam and Dean were still Hunters, just that they were working for an angel (I think it was Zachariah but I'm not sure). Dean is sick but doesn't want Sam to tell Castiel who's Dean's lover - I don't really remember why Cas wasn't there, just that it had to do with his "job".
When Sam can't pay the rent, their landlord (an angel, I just don't remember which one) tells him to earn the missing money by working in his night club/bar/something like that. The employees there get most of their money for going home with one of the guests each night. Gabriel ends up taking Sam home with him in order to save him from a violent guest who wanted him.
I think they then to this more often and finally fall in love but I can't remember the specifics of what happened later in the story.
Does anyone know this story?
ETA: Found. Link in the comments