Once a bright and upstanding District Attorney of Gotham City, Harvey Dent is hideously scarred on the left side of his face after mob boss Sal Maroni throws acidic chemicals at him during a court trial. He subsequently goes insane and adopts the "Two-Face" persona, becoming a criminal obsessed with the number two, the concept of duality and the conflict between good and evil. In later years, writers have portrayed Two-Face's obsession with chance and fate as the result of schizophrenia, bipolar disorder, and dissociative identity disorder. He obsessively makes all important decisions by flipping his former lucky charm, a two-headed coin which was also damaged on one side by the acid. The modern version is established as having once been a personal friend and ally of James Gordon and Batman, especially a very close friend, in most cases the best friend of his alter-ego, Bruce Wayne.