Of all the iconic comic book rivalries in the annals of pop culture, few if any have made the sort of impact as the one that exists between Batman and the Joker. Not only has the ongoing war between the Caped Crusader and Clown Prince of Crime come to define the tension of their shared city, it defines them as individuals as well. Unfortunately, that has left one of them with a deep-seated dependency on the other, and as far as the Joker is concerned, a life without Batman is barely worth living at all.
Source：https://www.cbr.com/dc-knight-terrors-joker-needs-batman/
