Erik either gets verbally abusive or physically abusive when he gets frustrated. Paul notes that when his brother gets frustrated, "All he can do is pace, "back and forth, back and forth, in the cage that he had made for himself." You can take your pick from any number of Erik's sociopathic behaviors. Erik, for example, has nearly blinded Paul, hit Paul's friend Tino to unconsciousness, and gets his goon to hit Tino's brother with a blackjack. This bad behavior represents frustrations that Eric harbors.