And by that I mean, has there ever been a good reason given by the writers why Batman hasn't killed the Joker. I'm only specifically talking about the Joker because I find it hard to believe someone in GCPD or Batman wouldn't have killed him.
Yes I know the reason is that once Batman goes down that path there's no turning back, but I really don't buy that at all when it comes to the Joker, the guy is a genuine monster. At the very least he should do a Batman Begins and not kill him but let him die in one of his own schemes rather than save him like he sometimes does. I also don't think he lets him live because he would miss him if he were gone, but it's an interesting concept.
So has anyone ever seen a different take on the reason why he won't kill him, or is the no turning back reason the only one, because I kind of feel like that's a cop out. Anyone have any interesting ideas of their own?
(Also as a side note, have any of his other villains done things that are outrageously psychopathic to put them near on a par with Joker that you think he really should have killed them too?)
(Also, I understand they obviously wouldn't kill off these villains as they are awesome, just wondering if you'd seen any good reasoning)