The Question and Answer section for Tangerine is a great resource to ask questions, find answers, and discuss the novel.
Paul remembers a black car that had a man with a ski mask hanging out the window holding a baseball bat. Paul jumped off his bike to avoid the blow. Paul ended up falling on the grass. Paul blames his sociopathic brother Erik for this.
I suppose the life lesson in Tangerine is to avoid being involved with dysfunctional people. Paul tries to do this at school but unfortunately the rest of his family are flawed.
The Fishers would most likely be considered a middle class family. We are not led to believe they're wealthy, and yet, Mrs. Fisher doesn't work outside of the home. Thus, I'd guess middle class.