Theo James and Rose Leslie on Taking a Romantic Leap With 'Time Traveler's Wife' (Exclusive)

Theo James and Rose Leslie reunite for a romantic drama with a timely twist.

HBO's The Time Traveler's Wife, the new six-episode adaptation of the best-selling novel by Audrey Niffenegger, follows married couple Clare Abshire (Leslie) and Henry DeTamble (James), whose marriage is complicated by time travel. Written by Steven Moffat (Doctor Who, Sherlock) and directed by David Nutter (Game of Thrones), the series also stars Desmin Borges as Gomez and Natasha Lopez as Charisse.

Prior to joining The Time Traveler's Wife, James and Leslie briefly worked together on Downton Abbey, though James admittedly doesn't recall their encounter. (Leslie portrayed housemaid Gwen Dawson, while James played Mr. Kemal Pamuk in a small season 1 arc.)

"We did, didn't we, Theo?" Leslie asked, laughing when the tidbit was brought up.

"Apparently we met on Downton Abbey but I didn't remember it," James confessed. "Maybe it's because I was very nervous! Rose was in the show, I was just kind of fleeting."

Years after their Downton experience, the duo will hit the small screen in the latest interpretation of Niffenegger's book. As Leslie and James explain, the attraction to the story and the script was immediate, with James adding that having Moffatt, Nutter and HBO behind the project made it even more enticing.

"All the boxes were ticked," Leslie told ET's Lauren Zima. "Theo and I have both said that just by reading the [script] whilst we were auditioning, it really hammered home the fact that we would love to have been a part of this project and so we worked hard to get it."

But it won't be the first Time Traveler's Wife, as the novel was previously brought to life on the big screen in the 2009 film with Rachel McAdams and Eric Bana. Leslie wasn't worried about any potential comparisons between the show and the movie.

"I haven't seen the movie and so I can't draw any comparisons... but I certainly read the book after I knew I would be playing Clare," she said. "But I also didn't want to overwhelm myself with too many versions of what this character is. I feel that Steven's writing is very rich. It is fantastic. There’s depth to it. There’s constant subtext to it and that was enough for me to feel like I was doing justice to Clare in this adaptation, rather than having tons of different versions of her in my head. And I felt the book was enough to draw on her past and her upbringing for me. But portraying her, I hopped on Steven's words."

Part of the hook for the time-traveling tale means James' Henry, who is thrust back and forth through the time continuum, finds himself naked every time he wakes up -- no matter where in the timeline he is. 

"Luckily it was not winter so that helped me out," James quipped when asked about his character's raw entrances. "It's so much a part of the DNA of the story that it didn't feel strange. And one thing we really worked on was trying to make this idea of time travel as rooted as possible so when he time travels, he gets thrown into another time. He doesn't know where he is, when he is. It physically exhausts him. He sweats, he's hungry, he's tired and it ages him quicker and then when he lands, he's completely naked with nothing, which is great for comedy. On one hand because it provides the show with comedy, but on the other hand, you're full of fear because there's a lot of danger in that and we wanted to play both."

"My only anchoring point was the book," he further explained. "He runs every day -- the idea in the book is that he has to run because it expels enough energy so he doesn't jump around in time. That's part of the law of the time-traveling so it was that kind of thing really, and you know, trying not to drink too much booze."

Because The Time Traveler's Wife jumps around in time -- his wife meets Henry for the first time when she's only six years old, for instance -- Leslie credited the production crew for helping her and James keep everything straight.

"Was it difficult? The production side of things were fantastic at scheduling each day for us and they were very accommodating in realizing that it would be lovely if we could just do one day as one age rather than changing from different ages throughout one particular day," she said. "We were lucky in being able to shoot this knowing where we were every day in the scene and we could ask our script supervisor whenever we needed to on what age we were doing and whereabouts we were in our relationship."

As for the old-age makeup, James said there were "various derivations of it." "I think it worked well with Rose. She looked instantly aged but elegant and touches of your own mom," he noted. "Mine, I think they went too deep and I looked like the head of a tortoise." 

"They went too far for the first camera test for Theo and then you guys called it back. And the final result was... you tinkered with it just right," Leslie agreed.

The Game of Thrones alum admitted she couldn't help but show off her aged look to husband Kit Harington: "I FaceTimed my husband straight away and he was chaffed!"

"I don't think my wife saw me because she would have been terrified," James joked. "I looked like Voldemort/Ursula."

Watch the trailer for The Time Traveler's Wife below.

The Time Traveler's Wife premieres Sunday, May 15 on HBO and will also be available to stream on HBO Max.

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