'Legion': Rachel Keller on Living Through the Romances and Nightmares of the Mind

The 'Fargo' veteran breaks down Syd's feelings toward David (Dan Stevens) and surviving her journey inside of his mind.
Michael Faye/FX

[Warning: this story contains spoilers through the first three episodes of FX's Legion.]

The mind is an incredible place, vast and deep, filled with an endless array of useful and useless information alike. It can be a dangerous place, too. Repressed memories can become monsters in an instant, derailing an otherwise peaceful day with nothing more than a flash to the past.

And that's just your average, everyday, run-of-the-mill mind. Now imagine the dangers contained within the mind of David Haller (Dan Stevens), potentially the most powerful mutant on the planet.

David's brain became a veritable hell-scape toward the end of the third hour of Legion, FX's X-Men series from Fargo mastermind Noah Hawley. During his stay at Summerland, a facility designed as a safe space where mutants can explore their abilities, David literally has been diving into his memories, hoping to uncover details from his past that can provide clarity for the future. Despite the best efforts of mutants like Melanie Bird (Jean Smart) and Ptonomy Wallace (Jeremie Harris), David's mind won't cooperate with the treatment, transforming into a full-on nightmare world in the episode's climactic moments.

Perhaps the rebellion of David's mind was exacerbated by the presence of a someone near and dear to David's heart: Syd Barrett (Rachel Keller), David's girlfriend and fellow mutant, with the ability to exchange bodies with anyone she touches. Syd and David's heart-to-hearts and moments of raw vulnerability have been a consistent touchstone of the series, certainly in this episode, as David muses that he still sometimes feels as if his body and Syd's body are one and the same.

At the very least, Syd and David occupied the same mind at the end of the hour, as Syd was forced to lead a childlike avatar version of her boyfriend through his brain's crumbling state. She makes it out alive, fortunate to only glimpse The World's Angriest Boy in the World — one of the more haunting figures from David's childhood — before shaking free from David's consciousness. While Syd, Melanie and Ptonomy all are able to awaken from David's nightmare, David himself remains sound asleep at the end of "Chapter 3," his fate unknown as we head into the fourth installment of this surreal series.

For further clarity on David and Syd's relationship, and her view of experiencing David's nightmare world, THR spoke with Rachel Keller about playing the Legion leading lady, and more.

As much as the series features the high-concept action and energy you expect from an X-Men story, Legion focuses just as much on the smaller moments, like the relationship between David and Syd. In last week's episode, David described it as a "romance of the mind." How would you categorize their relationship through three episodes?

I think that really encompasses what's particular about their relationship. What I really love is that this isn't a series where you're wondering if these two people are going to get together, or when are they going to get together. Do they like each other? I think it's special that when we start, they connect with each other. They become boyfriend and girlfriend. They love each other. The conflict is more about how do you maintain that unique friendship or relationship while you're doing this work? I think that repetition shows their support and their love, that maybe the details between them haven't been discussed. "Where did you grow up?" That's something that comes up later on. They understand each other, having that as their foundation. That's what was really enjoyable about exploring this relationship. We all have relationships with people where you feel inexplicably connected to them. When you're going through rough times, or somebody brings up something specific about your past and all that comes with that self-discovery, how do you then connect with someone? I love that scene in this episode where she tells him she's going to come with him [into his memories], and he goes, "Nope! I'm doing this by myself." You have to be able to say that to someone you love: "I need to be able to do this by myself." Obviously, they end up having a conversation about it, which, again, is so cool. How can I be more open with you, because I trust you and I love you? I think that's their romance of the mind.

David talks about how he still feels like he's Syd, after they swapped bodies in the first episode. Do you think that's part of their connection as well, that they were literally each other for a couple of hours at one point in time?

Absolutely. What a giving gift she has, to be able to say ... she ultimately later in the series wields it a bit differently, but to give up her body. For me as an actor, when I switch places with someone, I'm the other person, confused. They become the Syd that's maybe a bit more in control. I become the person who is stuck in this young woman's body. I can imagine for her what sense of self she must have to be able to give it up every time, and what that means for her and what that means for her new boyfriend. When I read that scene, I thought this was clever. How do they touch each other? How do they feel intimate? If they're switching bodies, that's one way. I thought it was handled with such class.

The episode also explores the darker corners of a relationship, as David warns Syd that she won't like what she sees when she travels into his mind. When Syd does get there, and David's mind starts going off the rails, she's very protective of David still. How do you view Syd's view of David's mind as they're traversing this nightmare world?

His wellness and his health is her priority. When it comes to loving someone and committing to their health, you may have questions and concerns, but with this kind of high-pressured situation, she becomes the angel on his shoulder, and the practical and logical one moving forward, because she so desperately wants to be with David in this quote-unquote "normal" way: have babies, have a home, let's just live a normal life. I think that's her driving force. If he gets better, then he will be all that she wants him to be, and they can become all that she wants them to become.

Syd tries to protect a younger version of David as his mind becomes a nightmare, and they race through a claustrophobic ventilation shaft to get away from the World's Angriest Boy in the World. What were some of the challenges from this scene? 

I had the pleasure of working with Luke, the young man who played the young version of David. I have to say, we became quite the pals. We played chess on our breaks. It was more about bruising. I'm a very easy bruiser, so I had bruises all up and down my arms and legs. That was my big question. I wasn't so claustrophobic. I don't mind the tight space.

How did you hold it together in front of the World's Angriest Boy in the World?

To be honest, I remember seeing the design for that guy and for the Devil with the Yellow Eyes. When you're doing costume fittings, you start to see the sketches evolving. "Oh, they're going to do that with them? Someone's going to wear that? What is that thing?" Seeing it all together in person, it was like, whoa. This is insane. It's amazing. Seeing it on the show? It's terrifying. It's terrifying even having seen it in person. The way they structured it, I got a little jumpy. I got a little gaspy. It surprised me and scared me. That's what we wanted, perhaps.

At the end of episode three, everyone's awake again, except for David. What are we getting into from here?

With the next episode, and really the whole series ... I think what I'm most excited about is how different each of the episodes are. When I watched the pilot, and then watched episodes two and three, it almost felt like a different show each time. I think we're given such a great lens through the X-Men genre, but we're also playing with film noir and thrillers and romantic comedy. It's a very director-driven show. It's almost like the episode prior doesn't set you up for how the next episode is going to go. It will connect. It will. But you have to experience it. You have to go on the ride and let the episode wash over you again. I think that's the magic of it.

What did you think of the latest episode of Legion? Let us know in the comments, and keep checking THR.com/Legion for more coverage throughout the season.