Whiplash
Short version?
A classic case of battered person syndrome.
Kid takes abuse from Vern Schillinger, but doesn't get swastika tattooed on ass, blames himself, turns on abuser and then goes right back for more abuse.
JK Simmons was essentially playing Vern from Oz. I can't decide if he's really an asshole who only plays nice in other movies or if he's really a nice guy who knows how to play an asshole. This character, Terrance Fletcher, is a carbon copy of the raging asshole he played in Oz. Just a mean son of a bitch. Oscar worthy? I don't know. Seems like playing a dick stain comes easily to Simmons.
There were some loose ends I didn't like. Why bother introducing the girl and building that part of the story only to let it fade away.
The film was a little ambiguous on whether the abuser was doing the abused kid a service by his abuse or not. My take was that the kid actually came at the very end to embrace and appreciate the abuse -- that the abuse made him better at what he does.
For that reason I decided I didn't care for the movie. There's no happy ending or moment of clarity when an abused person submits to more abuse.