Alicia Vikander, Michael Fassbender on their relationship, onscreen and off

For Alicia Vikander and Michael Fassbender, their new film The Light Between Oceans (in theaters Sept. 2) is something of a journey back in time. Both to the 1920s, when the gorgeous drama by director Derek Cianfrance (Blue Valentine) takes place, but also to 2014, when the movie's two stars met and fell in love while making it.

The film is based on M.L. Stedman's best-selling tearjerker novel, and in it, Vikander and Fassbender play a couple living in blissful seclusion on a lighthouse-capped island. But they are dealt tragic blows as Isabel suffers multiple miscarriages, before one day a rowboat mysteriously washes ashore with a baby on board. The drama that follows is heartbreaking, but the two actors fill their roles with incandescent grace notes.

Off screen, they are a public couple — she kissed him, after all, before accepting her Oscar for The Danish Girl last February — though they’ll never be accused of oversharing. Neither is active on social media, and on this weekend afternoon in downtown Manhattan, Vikander, 27, and Fassbender, 39, sit on opposite ends of a couch. Though they do, for the first time, address their relationship, calmly and efficiently, they would much rather talk about their work.

But that still includes the experience that brought them together. “ ‘Summer camp’ is something I’ve used to explain filmmaking to friends and family,” Vikander says. Fassbender adds: “You have to come together very quickly. That’s a very specific, unusual thing to this business — and it can be a very powerful thing.”

ENTERTAINMENT WEEKLY: When you’re playing lovers on screen and you begin to have feelings for your costar off screen, do you have to check yourself — like to be sure it isn’t a trick of your brain?

MICHAEL FASSBENDER: It wasn’t the first time in a movie either of us had played somebody who is falling in love. There is an element of separation there. If I’m playing a murderer, I don’t go out and start murdering people.

ALICIA VIKANDER: And I think we’ve made a clear statement that we keep certain things just between us. It was very easy to unite, but that’s quite personal.

Image Credit: Dreamworks

And I respect that. I'm not interested in asking all about your personal lives.

VIKANDER: [Laughing] Sure!

FASSBENDER: [Laughing] Sure, buddy!

But here's what I'm interested in. You've really managed to keep your private lives private. A lot of people in the spotlight don’t.

FASSBENDER: But that’s other people. Each to their own. I’m not going to talk about my private life with a total stranger, unless I feel like I need to. Why would I? I don’t.

But can you remember a time when you were curious to know more about the private lives of movie stars? That’s the impulse in your fans to know more about your relationship.

FASSBENDER: I might have been curious about actors’ lives when I was growing up. That’s human nature. We’re all curious about a lot of things. But my curiosity didn’t obligate them to tell me. It’s the worst thing if you’re sitting there in the theater, going, “Oh, that’s the guy who dates this person and likes to do this in the morning and that in the afternoon.” Then you’re just watching a brand, as opposed to an actor.

VIKANDER: I remember in Sweden, I used to set the alarm for 2 or 3 a.m. and get up with my mom to watch the Oscars. But for me, that was the same as the stories I saw up on the movie screen. Things have changed with social media and technology, but I still feel it helps when I know less about the actors I look up to. That’s what I mean — I love the mystery behind it all.

FASSBENDER: Exactly. The actors I looked up to when I was a teenager, they all just disappeared into different characters.

Image Credit: Davi Russo

Who were the actors that you looked up to?

FASSBENDER: All the usual suspects. Gene Hackman, Al Pacino, Robert De Niro, Meryl Streep, Brando, John Cazale.

Yeah, I don’t think of Hackman or Pacino and wonder about their personal lives.

FASSBENDER: It was a different time. Nowadays of course everybody’s got phones and cameras.

VIKANDER: Even people who don’t have the jobs we do. I’ve been asked a lot of question because I’m not on social media. But I did try Instagram when it came out, and I remember, just with my friends, feeling like I had to post things. And that was before I was really in films. And I know it involves a lot of other people who are not in the public eye. But it’s a pressure that you kind of have to do it. If you like it, then it’s great. And I do have a lot of friends who do communicate and express themselves and present their art through those mediums. That’s just the way we’re moving ahead. But I think you need to do what feels right.

Do either of you read reviews of your movies?

FASSBENDER: Unfortunately, yes. This fantastic actor Mel Smith, God rest his soul, we did a play together in 2005 or 2006, And he said, "Live by the sword, die by the sword." Usually you just remember the negative ones.

VIKANDER: Yep, again, it’s just human nature. You can hear a hundred nice words about yourself, and you’ll only remember the one bad one.

For more on Fassbender, Vikander, and The Light Between Oceans — including which performances of each other's they like the most — pick up the new issue of Entertainment Weekly, on stands Friday, or buy it now. Check back on EW.com for even more on the film — and don’t forget to subscribe for more exclusive interviews and photos, only in EW.