Kit Harington on His ‘Teenage, Morbid Fascination’ With Testament of Youth

When Kit Harington was in school, he was particularly moved by one particular book his class was assigned: the English pacifist Vera Brittain’s World War I memoir, Testament of Youth. Now, more than a decade later, he’s playing one of the story’s central characters in the movie of the same name, which hits theaters June 5. Harington, who made his name playing the complex and honorable Jon Snow on HBO’s Game of Thrones, plays Roland Leighton, an aspiring young writer with whom Brittain (Alicia Vikander) falls swiftly, utterly in love.

Testament of Youth is Brittain’s story, and Leighton’s chief importance is what he means to her—“chaperone, lapdog, humble slave,” as he describes what he hopes to be for her. It is the love Brittain feels for Leighton—and for the dear brother and friends who never make it home from battle—that she will channel later in life into her work as a peace activist. Harington’s Leighton offers plenty for Vikander’s Brittain to fall, and fight, for: He writes her poetry, takes her criticism as a challenge, encourages her to write when others expect nothing more of her than her marraigeability.

Harington, who also released a spy thriller in the U.K. last month, spoke to TIME about uncovering the real Roland Leighton, the person he was most eager to please with his performance and how he feels about being forever associated with a single role.

TIME: You’ve said that you had to fight for this role. What was it about the role that compelled you?

Kit Harington: The script, frankly. I was already doing a movie that was quite action-based, alongside filming Season 5 of [Game of] Thrones, so I wanted something which was more character-driven.

You studied Brittain’s memoir, Testament of Youth, in school. Do you remember how you reacted to it?

It was one of the things I studied that set off a real interest in this period of history and the literature surrounding the First World War. It’s almost a teenage, morbid fascination with what these young men went through, which was so horrific. This was what one woman went through, which was in many ways equally as horrific. Certain things you read when you’re a teenager in school you hate because you have to study them. This wasn’t one of them.

How did you go about getting to know your character, Roland Leighton?

There’s a book called Letters From a Lost Generation which was made up of letters that Roland wrote to Vera and Vera wrote to Roland and [Vera’s brother] Edward wrote to Vera, etc. They wrote to each other every two days or so. It’s amazing to have your character’s actual words to see who he really was. He was a sort of naive, silly young man. A very talented, intelligent, arrogant young man. But he was 19 years old, falling in love for the first time, thinking that going to war was the meaning of life.

Vera Brittain’s daughter, Shirley Williams, consulted on the film. Did she have notes for you on how to play Roland?

No, Alicia met her before starting the film. I met Shirley only afterwards. I didn’t feel any pressure playing Roland until I met Shirley, and then I wanted to know whether she felt I’d done the right thing, and I think she did. She thought the movie was a really great depiction of the book, and that was important to hear.

How did Alicia Vikander fit the image of Vera Brittain you’d had in your head from reading her memoir?

Vera is quite fierce. If you read her book, she’s got clear, very direct, strong opinions. Alicia is like that, as well. She really has one way she’s going to do it, and she’s going to do it that way. So in personality, they really fit each other.

There are a lot of scenes that are common to war movies, such as the tearful goodbye at the train station or the discomfort of waiting in the trenches. Did you feel any kind of pressure, or do you think director James Kent did, to approach these scenes in a fresh, new way?

I don’t think we were looking to do them in a fresh, new way for the sake of it. A goodbye scene at the station has been done many times before because that’s how it was. James needed some urgency in those scenes, and for that he played a quite urgent, hard house music. For anyone watching the trailer, this might just seem like a period war piece that’s been done before, but it has something new and fresh about it, definitely.

At least up to this point you’ve been best known for your role in Game of Thrones. Does it get tiresome always being associated with the same character?

No, I’m not tired of it. Thrones has done amazing things for me, and I have loved being a part of it. I just want to do stuff around it that’s a little bit different from here on in so that I’m not just turning over old ground. It’s great to have a character that you return to and that you’ve developed over a long time—I never resent that.

You’ve said that you’re interested in doing more theater. Between theater, television and film, do you feel more at home in one or another medium?

I haven’t done theater in awhile, and I’d like to go back to it. That’s what I trained in for three years. But TV and film are my home at the moment, and I’m loving it. I want to do it all. I’m greedy like that.