Re: The Joker's background?
It's alluded to in the movie that Joker doesn't really have a background. I mean obviously he is human and had to have come from somewhere, but he's made to appear almost supernatural in how enigmatic and, at times, omnipresent he seems. The best scene that illustrates this isn't even the multiple origin stories in my eyes, it's Gordon telling the Mayor what they have on him after Joker's been arrested, basically saying that he has no identity.
We are the music makers
And we are the dreamers of dreams