Natalie Portman analyzes why her May December character sleeps with [SPOILER]

"There's this question and danger about whether art can be amoral," she reflects.

There are certain ethical lines an actor shouldn't cross when portraying a real (still living) person — but in May December, Natalie Portman's character leaps over every single one.

When television star Elizabeth Berry (Portman) travels to Georgia to enmesh herself in the lives of Gracie Atherton-Yoo (Julianne Moore) and Joe Yoo (Charles Melton), her intentions don't seem all that noble. But considering that Gracie and Joe's marriage came out of a tabloid fodder affair that began when he was only 13 years old, she can be forgiven.

Until she begins to subsume Gracie's identity, slipping into her lisp and her physicality as she turns over all the stones of her life. Elizabeth takes things entirely too far when she sleeps with Joe, slowly seducing him until he gives into her and then turning on him the second it's over.

"She is not the most ethically sound researcher," Portman admits. "There's this question and danger about whether art can be amoral. In the class with the students, they ask her, 'Why would you want to play a bad character?' And she says, 'What a lot of us would say is that characters who do bad things are the most interesting, and it's about not judging your character. What we're curious about is getting into the heart of a human, which is always complicated and never perfect.'"

"When you go there and when you go into places that her movie is exploring — and trying to get into the mindset and the heart of someone who's committing a crime — what does that do to you?" she continues. "How does it affect you? How does it affect your morality and your ethics? Can art actually be immoral? Can you depict a crime without somehow endorsing it or exploiting it?"

Portman says Elizabeth's own blurring of the lines surrounding those questions is also a poignant examination of the challenges actors face playing truly deviant characters. "When you think about the number of movies that are made about serial killers and what an actor has to go into to get into the mind of that, it's a very intense thing," she says. "It's a very questionable thing. It's a debatable thing of how much we should go there."

We talked to Portman about why she wanted Todd Haynes to direct this movie (streaming now on Netflix), its parallels to her own life as an actress, and her fascination with themes of performance.