Batman Begins tone, their finished script bore more resemblance to a crime drama than a traditional superhero film. Comic-book influences included writer Frank Miller's 1980s works, which portray characters in a serious tone, and the limited series Batman: The Long Halloween (1996–1997), which explores the relationship between Batman, Dent, and Gordon. Dent was written as The Dark Knight central character, serving as the center of the battle between Batman, who believes Dent is the hero the city needs, and the Joker, who wants to prove even the most righteous people can be corrupted. Christopher said the title refers to Dent as equally as Batman. He considered Dent as having a duality similar to Batman's, providing interesting dramatic potential. Focusing on Dent meant Bruce Wayne / Batman was written as a generally static character who did not undergo drastic character development. Christopher found writing the Joker the easiest aspect of the script. The Nolans identified the traits common to his media incarnations and were influenced by the character's comic-book appearances as well as the villain Dr. Mabuse from the films of Fritz Lang. Writer Alan Moore's graphic novel, Batman: The Killing Joke (1988), did not influence the main narrative but Christopher believed his interpretation of the Joker as someone partially driven to prove anyone can become like him when pushed far enough helped the Nolans give purpose to an "inherently purposeless" character. The Joker was written as a purely evil psychopath and anarchist who lacks reason, logic, and fear, and could test the moral and ethical limits of Batman, Dent, and Gordon. Christopher and Jonathan later realized they had inadvertently written their version similarly to Joker's first appearance in Batman #1 (1940). The final scene, in which the Joker states he and Batman are destined to battle forever, was not intended to tease a sequel but to convey the diametrically opposed pair were in an endless conflict because they will not kill each other. Casting Describing how his character had evolved from Batman Begins, Christian Bale said Wayne had changed from a young, naive, and angry man seeking purpose to a hero who is burdened by the realization his war against crime is seemingly endless. Because the new Batsuit allowed him to be more agile, Bale did not increase his muscle mass as much as he had for Batman Begins. Christopher had deliberately obscured combat in the previous film because it