Justin Theroux has two careers in Hollywood: One as an actor, playing mostly intense characters in dark material (The Leftovers, Mulholland Drive, American Psycho), and another as a writer, in which he favors broad satire comedy (Tropic Thunder, Zoolander 2). “It’s dumb, isn’t it?” he laughs, very aware of this contradiction.

In person, his satire-writer side is far more apparent. For a guy who spends approximately 70 percent of his screen time crying or acting some degree of unstable, he’s all relaxed posture and easy smiles. It isn’t difficult to believe him when he says, “Taking my work home is never a problem.”

Theroux, who stars in The Girl on the Train as the ex-husband of Emily Blunt’s broken character, sat down with Inverse to discuss his writing and acting careers, the upcoming third season of The Leftovers, and more.

Warning: The following interview contains spoilers for The Girl on The Train.

How did you go about getting into the headspace to play Tom, a seemingly innocuous man with a dark side?

I would love to say I went to the library and pored over stuff and talked to a lot of professors and therapists, but it was a lot of Googling and I’ve known a couple narcissists. Not murderers, but in my own life, I’ve met a handful of them and seen the way they interact and behave.

Haley Bennett and Justin Theroux in 'The Girl on The Train'

It was one of the ways in which I gained entry into what that guy could look like, because I think that’s what [Tom] is. He’s not Max Cady in Cape Fear where he’s like, “I’m gonna fucking kill everybody.” He’s a guy who commits a crime out of — you could argue — necessity, although you never need to kill anyone. But it’s a crime of opportunity, and he hasn’t thought it through. He’s allowed himself to do it because he feels like a victim. Many narcissists feel like they are being victimized by bad people, when they are the actual bad person themselves. He sees himself as a victim. When his wife is essentially stalking him, he’s like, “Please, why are you doing this to us?” But behind closed doors he’s doing much more awful things as far as being faithful and having no remorse about it.

It’s a weird thing when someone is doing horrible things but able to behave normally. Even after murdering someone, he’s essentially watching TV and just shrugging it off. It demanded some kind of explanation as to why he could be so matter-of-fact in just living his life, and the way the movie’s structured, you don’t want to do any sideways glances that telegraph to the audience what’s happening.

Between drinking poison in The Leftovers and getting stabbed in the jugular in The Girl on The Train, you’ve had some interesting on-screen deaths lately.

Although, my guy in The Girl on the Train I don’t think goes to a wonderful hotel. Or maybe he does, who knows? Yeah, I’ve had some good deaths. I’m well-versed in drowning, shootings, corkscrews.

Rebecca Ferguson and Justin Theroux in 'The Girl On The Train'

What do you think is key to a good onscreen death?

Make a good face. No, it’s such a weird thing because as actors you go, “Yeah, I’ve driven a boat” or “I’ve done this,” but none of us have died, so we don’t really know what that looks like. I don’t know what the key is — good editing?

Between those two death scenes, were either one of them a bigger challenge for you?

It was a bigger deal for the jugular. It was a more complicated for The Girl on the Train, with the corkscrew just as far as the prosthetic neck; the tube that pumps blood and gushes and all that. For drinking poison, I just had to put an Alka-Seltzer in my mouth and fall on the ground.

Is there a scene in The Leftovers that was your favorite to film?

I loved the sequence in the well with Patti. I thought that was an astounding piece of writing, from the moment that Kevin puts it together that Patti’s that little girl in the hotel room and he walks to the well and he has to push her into it. I remember reading it like, “And then he pushes her into the well,” and then turning the page and seeing more writing and going, “What could possibly…?”

To me, that’s your fade-to-black moment, and then to see this beautifully-written scene of Patti in the well and then having to put her out of her misery a second time was so heartbreaking. And the story she tells, and about Jeopardy where she sort of confesses her weakness — to sit across from Ann Dowd and watch her do that monologue was sublime. She’s such a wonderful actress.

Damon [Lindelof] really swung for the fence on that one and it paid off. I was very moved by that script. To me, it’s really Patti’s episode. I thought that was a beautiful sleight of hand to take that character and humanize her and make her so special. I just couldn’t believe it; I was in tears reading it at the end. And I was glad that we had the technical and creative ability to pull it off.

Will you revisit that metaphysical space again in Season 3?

There’s so many bizarro twists and turns and special episodes. Crazy, crazy things happen. Like Season 2; like Season 1. I think Damon again was writing from a very strong place and it’ll be its own thing — it’s a big location change again — but it’s definitely still our show. It will not be unrecognizable as The Leftovers, and I think it will be very satisfying. I’m confident that we have a good final season in the can.

It’s interesting that in your acting you gravitate towards intense and dark characters, but in your writing career, you tend towards comedies.

Dumb, isn’t it? I like doing comedies too, but boy was The Leftovers a lot of drama. I like to think that I can do both, but just for the last couple years, it’s been a lot of dramatic stuff for the most part. I could never write a Leftovers script. I don’t think that way — at least in writing. Maybe I would if there was an idea that struck me, but when I look at scripts like Girl on the Train, I go, “I don’t think I could write this.” My brain just doesn’t work that way. I think if you’re a painter and you do abstract art, you’re not going to really go do figurative art just to try it. But if there was something I felt passionate about that happened to be dramatic, I would definitely take a stab at it.

Justin Theroux in 'The Girl on The Train'

And since you do play very intense characters — as Kevin Garvey you have to cry possibly more than any other man on TV; in The Girl on the Train you access a lot of rage — what’s that like for you?

For emotions in general — whether it’s crying or laughing or being rageful — they multiply as you access them. There are times in The Leftovers in particular where you’d have to be upset and then the more upset you get, the more upset you get, if that makes sense. It’s like laughter: If you and your friend are joking around and then you do something stupid and then you guys start laughing about it and then you start laughing harder because you’re laughing. At the end of a good laugh, or a good cry, there’s something cathartic about it. I won’t go so far as to say it’s therapeutic — but you’ve gotten rid of something, or you’ve unburdened yourself from something.

So a lot of times, I’d leave the day at The Leftovers, or even on Girl on the Train, and feel better, like, “Oh, I’ve gotten some rage out” or sadness, out or whatever it is. I’m not the kind of actor who takes stuff home and is sad all the time over breakfast. It was all wonderful experiences.

And now for the most pressing question about The Leftovers Season 3: Will Kevin reunite with his dog?

I hope Kevin reunites with his dog!

The Girl on the Train is currently in theaters. The third and final season of The Leftovers will air in 2017.

This interview has been edited for brevity and clarity.