Ledger's deranged take on the Joker notably never gave much information regarding the villain's backstory, something other Batman films had been all too eager to do. Nolan has previously made it clear he was against the idea, and now screenwriter David S. Goyer has revealed that Warner Bros. actively pushed to get an origin story for the character at one point.
"I do remember when we were talking about, 'Well, what if the Joker doesn't really have an origin story?" said Goyer during a Comic-Con@Home interview. "Even after the success of Batman Begins, that was considered a very controversial thing, and we got a lot of push-back. People were worried." Goyer was given a story credit on the film, writing the original script treatments in the early stages of development, but the finished script was written by Nolan and his brother Jonathan (of Westworld fame).
Thankfully, Nolan and the rest of the team were able to get their way, and instead Ledger's Joker deliberately muddied theories surrounding his origin. At multiple points throughout the film, which won Ledger a posthumous Oscar for Best Supporting Actor, he would tell different characters how he got his scars. Of course, each story offered a different explanation, leading to a depiction that's all the more frightening.
Watch the full interview with Goyer above.