Superman: Emperor Joker. Action Comics #770 (Part 9).
This portrayal of Batman/Joker dynamic may seem rather exaggerated and superficial. However, the comic book captured some vital aspects of their relationship. For example, Joker’s attitude towards Batman is usually ambivalent, in a sense that he wants to preserve their relationship, but at the same time, he does everything to destroy it.
In the comic book Joker gains powers that make him omnipotent and unstoppable. But, as it turns out, there is a serious limitation to Joker’s capabilities – he can destroy everything (including time and space), except for Batman. He keeps murdering Batman, only to bring him back to life later. He doesn’t seem able to get rid of his foe permanently. It is explained in terms of an obsession and cognitive distortions (Joker isn’t capable of getting Batman out of his head). But that’s a rather shallow explanation.
Anyway, the pattern repeats itself quite often in the other comics, too. Joker strongly believes that he has control over it and could end “their game” any time he wanted. But in reality, the mere existence of Batman undermines his fantasy of omnipotence.
The comic book also proves that Joker’s inability to kill Batman reaches deeper than his rationalizations (such as: I won’t kill you, because you’re just too much fun) might suggest. Here, Joker’s emotional dependency on Batman renders him most vulnerable, but on the other hand, it’s the only thing that sets limits.