Batman: The Killing Joke poster
The novel deeply explores the psychological connection between Batman and the Joker. They are portrayed as two sides of the same coin, both shaped by tragedy but responding to it in vastly different ways.
The story concludes with a beam of light going out, leaving it unclear whether Batman has finally crossed his own moral line by killing the Joker or if they continue their endless cycle of conflict. This ambiguity reinforces the psychological complexity of their relationship and the overarching themes of the graphic novel.