The "Gladiator" star was initially reluctant to sign on and portray Batman's twisted nemesis in the origin tale - and so he asked his sisters and mother for input at a get together.
"My whole family read it," he tells WENN. "It's not a standard practice but we were all together at the time and I was making the decision and was curious what they thought."
"We had a lot of discussion about it. There were no easy answers and a lot of questions it poses and so it made us all think, so I guess I anticipated some of it (controversy)."
But not even director Todd Phillips could anticipate how much drama the film would stir up before its release on Friday, October 4.
"I've acknowledged that it's a complicated movie but I never imagined the kind of discourse that it has reached in the world," he explains. "I think it's interesting that it sparks conversations and debates around it. It's great to talk about it, but it's much more helpful if you've seen it.
"There's been so much said by people who haven't even seen the movie. There have been think pieces by people who have said, 'I haven't seen the movie, I'm not gonna see the movie, I don't need to see the movie', and then they write two pages about the movie."
But all the fuss served the film well - it broke October release records at the global box office over the weekend, grossing $234 million.