The Joker has always thrived on chaos, however, in the Emperor Joker storyline, DC reveals that Joker doesn’t want a universe ruled by anarchy. Batman’s nemesis has always been his opposite—creating chaos so that Batman can restore order. Batman and Joker's rivalry is one of comics' greatest, driven by Joker's obsession with the Bat. Joker prides himself on his insanity and enjoys toying with Batman, claiming that the Dark Knight is just as twisted as he is. Upon further inspection though, this obsession could almost be a desire for what is unattainable for his fractured psyche.
In Emperor Joker, the Joker takes 99.99% of Mister Mxyzptlk’s powers over reality, transforming him into a god-like being who can reconstruct the universe how he sees fit. With unlimited power, Joker can do whatever he pleases. This includes eating the entire population of China; taking Lois Lane to be his empress; and torturing, killing, and resurrecting Batman every day for his own pleasure. There appears to be no rhyme or reason to Joker’s actions. However, there’s a small part of Joker that cannot stand life without order and meaning.
In Action Comics #770 by Joe Kelly and Kano, Emperor Joker plans to destroy all life in the universe, even his own. Superman begs him to consider the implications, but this decision seems different from the Joker’s usual spontaneity. In a moment of weakness, Joker begs Superman to stop him, to stop the voices before it’s too late. While this may be passed off as another of his jokes, a conversation with Harley unveils the truth. Joker doesn’t wish to destroy the universe just for the fun of it—he believes that by starting anew, “for the first time, chaos will be replaced by order” and he’ll fix everything, “leaving behind a clean, quiet universe. A place where people like [him] won’t ever come into existence.”
For all Joker crows about chaos and nihilism, it appears his ultimate desire is for a universe that makes sense. At the time when Joker is most powerful, he also appears to be most vulnerable. He’d rather have a world without him than for the madness to continue. Behind the clown makeup, DC reveals that Joker still experiences pain and, perhaps, regrets the pain he has inflicted on others. He idolizes Batman, a symbol of order and justice, and the only person who can keep him in check. Ultimately, it's Joker's inability to let go of the Batman that allows Superman to break through Joker's reality so that Mxyzptlk can reclaim his power.
Emperor Joker is oddly enough, one of the more introspective and self-aware versions of the character. It can be argued that Batman gives the Clown Prince meaning and a reason to go forward each day—be it another prank or one last laugh. When Joker receives unbridled power, not even he can be satisfied, and without Batman, his insanity grows too great to handle. Even the world's most deranged villains appear to have their limits. It's funny, isn't it?