Batman is a dark and brooding hero with a personal vendetta against crime and injustice. Psychologically traumatized by the death of his parents, Batman has sworn to rid Gotham of the criminal elements that took his parents away from him. He is extremely pessimistic and suspicious, which often makes it difficult for him to trust people other than Alfred, Commissioner Gordon, Lucius Fox, the Robins, or Batgirl. Despite this, Batman has proved to have a great love for humanity, which was instilled by his parents. His father was a doctor, while his mother was a crusader against child abuse. Indeed, Batman's oath of vengeance is tempered with the greater ideal of justice. He refrains from killing, as he feels this would not make him any better than the criminals he fights. To protect his secret identity, Batman has constructed a fake persona he can use in his civilian identity. To the world at large, Bruce Wayne is a self-absorbed, irresponsible playboy and philanthropist. Only his closest allies know that this attitude is just an act.