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.
O Captain! My Captain! Rise up and hear the bells.
Rise up, for you the flag is flung, for you the bugle trills.
For you bouquets and ribbon'd wreaths, for you the shores a-crowding.
For you they call, the swaying mass, their eager faces turning.