Originally Posted by
bat39
I think at this point, the Red Hood aspect to his origin is pretty much firmly cemented in canon. Its the only way Jason Todd being Red Hood makes sense, and its been a fact in comic-book continuity since 1951!
That said, one of my personal headcanon origins for the Joker is that he was once a GCPD cop who, like Jim Gordon, wanted to fight crime and corruption. He tried to take on the Mob, and corrupt cops, but didn't succeed and only put himself in a precarious position, professionally and even in terms of the safety of his life and family. Then, Batman showed up and became a hero for taking down corrupt cops and ganglords and he started to resent Batman a bit for doing what he wanted to do and not having to face the consequences. Then, his wife and kids are murdered (by one of the monsters and/or corrupt cops he tried to take down), and this sends him on a downward spiral. He figures out that the only way to take down the corrupt is to be like Batman and not follow the rules, so he adopts the identity of 'Red Hood' and starts destroying and/or stealing from the Mob. During one of his 'revenge missions', he shows up at Ace Chemicals, and ends up in an altercation with Batman, falls into the vat of chemicals, and by then his already unhinged mind snaps, coupled with the scarring and white face/green hair, and he becomes the Joker.