Despite their bloody, brutal history Batman and the Joker have an odd bond that may be rooted in a unique trait they share. Lex Luthor's interrogation of the Clown Prince of Crime highlights a similarity between the Joker and his beloved Batman.
Ever since the Joker first burst into the Dark Knight's life, there's been a powerful connection between the two that practically eclipses most other hero/villain relationships. Like many classic antagonists, the two stand for virtually opposite values, with Batman continuously trying to establish order and Joker embracing chaos to the fullest. Despite being bitter enemies, Batman and the Joker aren't entirely dissimilar and several outsiders have noticed a level of obsession is shared between the hero and his archenemy. Batman may have more trouble admitting how focused he can be on his most hated foe, but the Joker readily accepts that Batman occupies most of his thoughts.
Related: Joker Stealing Bruce Wayne's Money Was Pointless, DC Admits
The source of this shared obsession might have revealed itself when Joker sat down for a conversation with Lex Luthor of all people. In Action Comics #897 by Paul Cornell and Pete Woods, Lex is continuing his mission to attain cosmic power after his time as an Orange Lantern, the Green Lanterns' rival Corps. Luthor tracks down a mysterious energy source in Arkham Asylum, but the energy is contained in the cell of the Joker. Luthor manages to get himself inside the Joker's cell and, against the advice of his team, has the camera turned off to let the Joker speak freely. Lex implores Joker to take the situation seriously, to which the Joker responds "I think if I can just kill Batman, I'll save the world!" Luthor finds the aside intriguing,
Read more on screenrant.com