I'm surrpised no one has posted such an obvious pick. The ending completely shifts everything we viewed previously. The black teacher is revealed to have only "helped" Derek so he can groom him to be a Nazi spy for the police, never giving a fuck in actuality about his well being or him changing. He renounces his ideology only for it to mean squat due to what I just mentioned and his brother being killed for a slight offense he made to some joggers who shoot him dead over it. He shat all over his skinhead friends and girlfriend due to some misguided (and ultimately bogus) journey to redemption which was just to make him into a rat by the black teacher. He either goes full nuclear and goes to a ghetto and shoots at everyone he sees or just kills himself.