Incest sex
I was reading about this on Wikipedia, and it seems a common trope these days in remakes to give oodles of motivation and backstory for the killer when mystery served them better the first time around. I read how Billy's mother couldn't get pregnant by her boyfriend, so she went upstairs to where Billy was locked away, raped him and conceived Agnes. Jesus! How the hell is that presented in the film??? Do we see bits of it, or is it done by character explanation???
Everyone else may be an a**hole, but I'm not! - Harlan Ellison