The Joker has been a foe of Batman's since Batman #1 (April 1940), almost since Bruce Wayne donned the cowl in Detective Comics #27 (May 1939). But even though we've seen him kill, maim and torture, all in the name of fun, we know precious little about the character. But writer Scott Snyder knows more than we do. And he's giving us some hints.
Snyder spoke with IGN about the Clown Prince of Crime, and said:
[W]e saw a brand new origin for the Joker that explained how he has a regenerative quality -- linked to Vandal Savage, Ra's al Ghul, and the Talons -- that not only grants him unnaturally long life, but the ability to heal from fatal injuries. Last issue, Jim Gordon discovered pictures of the Joker dating back to the beginnings of Gotham, and this issue appeared to confirm that the Joker is older than Gotham....
[T]his is where he says, "Guess what? I've always been immortal, and now I'm closing the door on you, little mortal Bruce Wayne."
And as Snyder told Comic Book Resources, while the Joker comes across as crazy, actually ... he's not.
The Joker never says he's crazy. He more, unapologetically, says, "This is who I am." He very much has reasons for doing the things that he does, which make sense in his relationship with Batman. But I don't think he views himself as crazy, and I don't think Batman thinks he's crazy either. The public perception of him is that he is a lunatic, but deep down, he's actually very evil.
Just how evil? A recent story arc, "Death of the Family," saw the Joker kill multiple policemen/innocent bystanders, capture every member of Batman's extended family, bandage their heads and douse them in gasoline. But before he attempts to make good on his promise of immolation, he convinces Batman that he has surgically removed their faces.
He didn't. But he did admit to Catwoman that he loved Batman ... in a non-romantic way.
Previously, the closest thing to an origin story we've seen from the Joker was Alan Moore's The Killing Joke (1988). There the Joker revealed that he was a mediocre comedian with a pregnant wife. But the happenings of one bad day, which resulted in the death of his wife and the chemical accident that ruined his face and mind, made him the criminal we know and love to hate. Of course, the Joker is an unreliable narrator, so readers had previously that surmised his tale of woe was a lie.
But knowing that the Joker is an immortal, evil clown, we'll never look at Stephen King's It the same way.