8 Theories About The Origins Of Heath Ledger’s Joker
2. He Didnt Exist Until Batman
The first chronological appearance of the Joker in The Dark Knight Trilogy is the calling card revealed in the little tease at the end of Batman Begins. And that's really the extent of his pre-Dark Knight origin; he existed by the time the bat signal had become a permanent fixture on the skyline of Gotham. Well, what if he'd only just started existing; could Joker actually be a reaction to Batman.
It's very much possible - Gordon doesn't talk about him like he's a long-standing criminal - and thematically it strengthens the duo's relationship in The Dark Knight. One of the central themes with the Joker that has become more and more integral to the character as time's gone by is that he and Batman are dependent to some degree on the conflict between them. This pushes it even further; you essentially have a Joker who is obsessed with Batman
Gordon's line about escalation between the mob and the police, delivered just before the reveal, adds to this; Batman has cape-and-cowled up to take on the mob, and in direct reaction the criminals start to develop a taste for the theatrical themselves.