What is the Joker's motivation?

[The Dark Knight]

Brilliant post, colors.

[The Dark Knight]

I've dug up an ancient thread, but I was thinking about this topic the other day.

I do think there's more to the Batman/Joker relationship than a simple revenge story. Jack Napier is presented as a narcissist; when he is disfigured, he not only begins disfiguring everyone else, but he starts actively seeking the spotlight.

He gets into a war of showmanship with Batman, who's trying to avoid the press and avoid any real human contact, and yet still gets more headlines than the Joker. Myth and secrecy is a bigger mystery to people.

This Joker is out to "out-do" Batman in theatricality and absurdity - namely by killing people. Batman is struggling to find the pattern in his toxin, and gets unintentional headlines by opposing the Joker.

So beyond the revenge story, there is something of a combative relationship, similar to themes that have at some point or other appeared in the comics.