Bobbie's Flashback

Tonight is the first time I have seen the entire movie from the first scene to the last. Therefore, I had missed this scene before, but now it raised questions.
When Bobbie is recovering from the beating he got from the security guard while robbing the vending machines, there's a scene where he's looking in the mirror at his battered face and he kinda of drifts into a childhood flashback. In the flashback, he is in the middle of a domestic fight between his mother and a man that looks like he is supposed to a younger James Woods. After beating his mother, this man turns and picks up Bobbie and throws him against the wall. This flashback occurs after the scene where James Woods comes to their apartment and gives Bobbie some heroin to help him with the pain from the beating.

Then in another scene right afterwards, Mel picks up Bobbie on the street in his new Cadillac, and he starts asking him how old he is now.....

Was Mel his stepfather? Or mother's ex-boyfriend? It was never really brought out in the movie. The boy who is Bobbie's roommate, Danny, is Mel's nephew, as he states when Bobbie asks him why he doesn't recruit Danny instead of him to show the ropes.

Also after the diner scene when Bobbie and Rosie get so drunk that they have to be carried home and put to bed, Bobbie looks up at Mel and says "Goodnight Dad".

That line never had any implications other than Mel being a mentor/father figure to Bobbie, as he initiated him into a life of crime. But after seeing the earlier scene with the flashback, that line took on a whole different meaning.

I haven't read through every thread, so I don't know if anyone brought this up before, but since it was just on Sundance tonight, maybe someone will go on the boards and answer this question.