Can you tell me one of your favorite lines from that movie?
The whole scene with Bender telling Andy about his home life "smoke up Johnny!"
Is that a reference to cigarettes?
Yes, it is! His father says his father got him a carton of cigarettes for Christmas.
I bet that that probably messed him up in the head. 
Oh for sure, he gets into trouble a lot and has to go to detention for the next 7 weekends.
Seems like he's an anti-hero. Perhaps that's part of what makes his character real and interesting.
I do not think there is any one hero in this movie, all of the characters seem so real and interesting. It is raw and I feel like anyone can relate to at least one of the characters.
Interesting that this movie deviates from the typical norm of the underdog hero that rises above challenges and comes through in the end by surprising everyone and succeeding. Is there not any element of this in John Bender's story? 
One could say there is. He treats Claire better by the end and sort of becomes friends with the other characters but there is no way to know if this will continue on Monday.
People don't change easily, it's unrealistic to expect them to... I suppose that adds to the realness aspect of the movie. He goes from self-destructive to slightly unstable, that an improvement! 
I think another real factor of the movie is all the characters start as enemies, but join forces and put their differences aside to work against the prinicpal.