My Thoughts On The Joker are long and complicated, but my main theory is that he is not just insane, he's also metasane. I have decided that he gets confused about things like his origin because as far as I can tell, he remembers everything--and he remembers it not in his world's chronological order, but the order it's written in. So sixty-odd years of AUs, retcons, genre reboots--he seems to get them all mixed up. And he's obviously aware of the fourth wall.

God help us if he remembers the fanfiction.

Also, Mark Hamill is The One True Joker. That is all.