There are several examples of irony throughout the novel Monster by Walter Dean Myers. At the beginning of the novel, Petrocelli refers to Steve Harmon has a "monster." Ironically, unlike the other people involved in the robbery and murder of Aguinaldo Nesbitt, Steve is depicted as the most introspective, sensitive person in the novel. Steve Harmon wrestles with his conscience and identity, which humanizes his character.
Another example of irony includes the attitudes and personalities of the various witnesses. Osvaldo Cruz is a selfish criminal who acts like he is tough and threatening. Ironically, Osvaldo says that he was scared and forced into participating in the robbery. Other witnesses are also notoriously immoral individuals who act like they are good people trying to do the right thing.
Throughout the novel, O'Brien helps Steve Harmon by encouraging him and attempting to portray Steve in a positive light. Ironically, when Steve is found not guilty, O'Brien looks at him like he is a monster. O'Brien believes that Steve was guilty, and her attitude towards him after winning the case is unexpected.