Re: The Joker's background?
I think anyone who came to conclusions in the way Joker did, would go mad. It's enough to make anyone off themselves. No point in life, existence can't be comprehended? It's bad.
I'm basing it purely on studies and research I've personally done.
Joker cracking up upon a philosophical revelation, that disturbed him immensely, it's realistic to assume he may have attempted suicide, only to survive. Then his mind came out more twisted as he repaired himself.
I'm kind of basing this theory on Joker attempting to kill himself in Gotham By Gaslight. He survived, but his face and mind were damaged by the poison he took.
Joker by all means, has stared death in the face and laughed at it. He's seen the void in existence. None of us can comprehend the psychological damage he's experienced.
"You can't make an omelette without breaking some eggs - hehehehehehehehe "