Heath Ledger's Joker performance in The Dark Knight is pretty much legendary, in part because of how devoted to the character he became. That even resulted in getting punched on set by Batman himself.
Christian Bale portrayed the part of Batman in Christopher Nolan's trilogy and recounted a few behind the scenes moments from the set as part of a new book 100 Things Batman Fans Should Know & Do Before They Die. Author Joseph McCabe interviewed Bale and Nolan in 2008 and had the chance to speak with Ledger in 2007.
One of those behind the scenes moments takes place in the fantastic interrogation scene, where Ledger got Bale to actually hit him (via THR).
"As you see in the movie, Batman starts beating the Joker and realizes that this is not your ordinary foe," Bale said. "Because the more I beat him the more he enjoys it. The more I’m giving him satisfaction. Heath was behaving in a very similar fashion. He was kinda egging me on. I was saying, “You know what, I really don’t need to actually hit you. It’s going to look just as good if I don’t.” And he’s going, “Go on. Go on. Go on….” He was slamming himself around, and there were tiled walls inside of that set which
Crazily enough that Interrogation scene was Bale's first scene with Ledger, and set the tone for the rest of the film.
"I saw that he’s a helluva actor who’s completely committed to it and totally gets the tone that Chris [Nolan] is trying to create with this," Bale said. "We’re not going for actors revealing their enjoyment of playing a wacky caricature. We’re treating this as serious drama."
Ledger's method acting was something he kept up throughout production, but Bale also remembers the person behind the character.
"You go into character and you stay in the character," Bale said. "I love that. I find that so ridiculous that I love it, and I take that very seriously. Heath was definitely embracing that. When he was in the makeup and the garb he was in character the whole
100 Things Batman Fans Should Know & Do Before They Die is in bookstores now.