Bruce Wayne wakes up to a world where his parents, Thomas and Martha Wayne, were never murdered. In this "ideal" life:
Bruce begins to suspect the reality of his perfect world when he tries to read a newspaper and books, only to find they contain . This is based on the psychological concept that the reading part of the brain is inactive during dreams, a detail that has become a legendary piece of Batman lore among fans. Highlights & Legacy Batman: The Animated Series Season 1 Episode 26
Kevin Conroy famously cited this as his favorite episode, as it allowed him to play Bruce Wayne with a range of confusion, joy, and eventual fury. Perchance to Dream - Batman:The Animated Series Wiki Bruce Wayne wakes up to a world where