(This video contains only german language or Dialogues and Monologues.)
Witnessing the murder of his parents as a child leads him to train himself to physical and intellectual perfection and don a bat-themed costume in order to fight crime.
Nolan's inspiration for The Dark Knight was the Joker's comic book debut in 1940, the 1988 graphic novel The Killing Joke, and the 1996 series The Long Halloween, which retold Two-Face's origin.
Throughout the film, the Joker states his desire to upset social order through crime, and comes to define himself by his conflict with Batman. To prepare for the role, Ledger lived alone in a hotel room for a month, formulating the character's posture, voice, and personality, and kept a diary, in which he recorded the Joker's thoughts and feelings. While he initially found it difficult, Ledger eventually generated a voice unlike Jack Nicholson's character in Tim Burton's 1989 Batman film. He was also given Batman: The Killing Joke and Arkham Asylum: A Serious House on Serious Earth, which he "really tried to read and put it down."
