Regarding the proposition of Gotham City's destruction, there was a very curious phenomenon: the inverse Dark Forest Law. It went like this: when either Batman or Joker held the nuclear launch button, the possibility of Gotham's destruction dropped to its lowest point. And when both of them held nuclear launch buttons and knew the other did as well, Gotham absolutely would not be destroyed.
It sounded counterintuitive. By ordinary reasoning, a nuclear launch button was exceedingly dangerous in anyone's hands, because the human heart was unfathomable—let alone in the hands of two people whose mental states could hardly be called stable, like Joker and Batman.
But if one carefully analyzed things according to their logic, there was indeed some sense to it.
First, according to the Batman Joker aggregation law, all of Joker's actions revolved around Batman. If Joker obtained a nuclear launch button, it would certainly be to threaten Batman, and the moment a nuclear weapon was most threatening was when it had not exploded.
Joker would not press the nuclear launch button, because he only wanted Batman to laugh, not to die. The purpose of all Joker's actions pointed toward Batman, not Gotham. If something merely destroyed Gotham without allowing Joker to witness Batman's struggle and conflict, Joker would not use it.
Likewise, if Batman held a nuclear launch button, he would not press it either. If he did, Gotham would be destroyed, but Joker would not be. Then another city would become Gotham all the same, making Gotham's destruction meaningless. Pressing the button would be unnecessary.
And when both of them held nuclear launch buttons at the same time, they would certainly know the other would not press one, and know that the other knew they would not press one either. Such a test was meaningless to