2008's Going Sane is a four-issue storyline (#65-#68) taken from the comic book series Batman: Legends Of The Dark Knight. The story highlights the importance of Batman to The Joker: he isn't just the scourge of his criminal existence, he's also a necessary aspect of his life as a whole. It depicts what happens to the Clown Prince of Crime when he kills (or at least believes that he kills) the Dark Knight: he transforms into a normal, sane individual. He gets plastic surgery to make himself look like an average man, calls himself "Joseph Kerr", blocks out all memories of his bloodstained criminal history and even falls in love with a normal woman - but it proves to be a temporary change, as Batman seemingly returns from the dead. It's an awesome take on the mythology and one that emphasises exactly why the Batman/Joker rivalry is so long-standing.
