M. Night Shyamalan has another spooky idea for you: In his latest film “Split,” James McAvoy plays a traumatized man whose brain has formed 23 different personalities. They take turns inhabiting his body, meaning the actor has to play such characters as a stern man with OCD, a young boy and a kindly English woman. The film begins with him kidnapping three teenage girls, locking them in his underground lair, though it would be a spoiler to reveal what he has planned for them. On top of being a new M. Night film, it also features, as one of the captives, Anya Taylor-Joy, the break-out star of last year’s “The Witch,” who Shyamalan discovered before the film had premiered and made her a name.
You’ve said you were struck by the subject of Dissociative Identity Disorder (DID) a long time ago. What made you return to it?
There are certain subjects that always stick with me: Aliens, ghosts. This was one of them: the idea of the human brain being many, many people in the human body. And it’s not just personalities, it’s different human beings in the same body. That is unbelievable.
James McAvoy signed up for a lot of work, playing numerous characters with distinctive personalities.
I don’t know how I would have done it without him. When I looked to see who could play this role, there was really just a handful of men who had the buoyancy, the physicality, the emotion, drama, the craft to play this role. Because you didn’t want it to be silly. You want it to be right on the edge of poignant and funny. And he had been versed on the subject of multiple personalities before me. He was thinking about doing a movie [about this] a long time ago. So, I was very lucky in having a world class actor who already knew the subject. It was amazing. He wasn’t afraid of long takes. Some of the takes were six to eight minutes long when he was doing the therapy sessions. He didn’t even blink. He is very courageous.
Anya Taylor-Joy became a name a year ago with “The Witch,” but you actually shot the film before it’s Sundance premiere, before she was a Next Big Thing. How did you find her?
She auditioned with all the other girls on tape, and then I saw it and said, “Who is this?” I brought her in with a couple of other girls, but I knew she was the one. She is just a special actress. If she wants it, she will probably be one of the biggest stars in the world someday.
Looking at the film’s final cut, is there anything you would have done differently?
The way I shoot movies, I ask myself that same question. Then I do reshoots. I call the actors and I say, “I didn’t like that scene, could you come back and redo it?” And they are so sweet, they all come back. I think I reshot four times [on “Split”].
And how do you know when to stop reshooting and call final cut?
You know, you watch it, you put it in front of an audience and then you see them moving with it. It all feels suspenseful and there are no bumps. You feel the emotion growing and it kind of blooms like a flower. So once you have that feeling, it feels right.
What is the main message you want the audience to get from this movie?
It’s a very complex movie where the bad guy maybe isn’t a bad guy. The things that have damaged us in the past, do they make us weaker or do they us stronger? That is the question.
WARNING: THE REST OF THIS INTERVIEW CONTAINS A SINGLE SPOILER: Did McAvoy have to do a lot of physical training for this character?
Yes, he did. We had him work with a trainer. He needed to be very physical and imposing. He is already very fit. So we were already starting at a good place, but he did work with a trainer.
Is the beast all natural?
That is 98 percent him. The veining we added, but that is him.