Elliot Page is getting candid about his sex life.

The actor, who came out as transgender in 2020, recalled the first time he had a "suitably consensual" sexual relationship with a woman, writing in his new memoir Pageboy that he and co-star Olivia Thirlby had sex often while filming the 2007 movie Juno in Vancouver. 

"I was taken aback the moment I saw Olivia," he wrote. "Embodied and bold, her long brown hair moved in slow motion. We were the same age, but she seemed so much older, capable, and centered. Sexually open, far removed from where I was at the time. But the chemistry was palpable, it pulled me in."

Page, 36, called himself "embarrassingly shy" around the actress, who played Leah opposite his pregnant character Juno.

"She had much more experience," he said. "I was closed off. It was rare I let anything in, but I felt comfortable with her, and I began to poke my head out of its shell. We became friends quickly, spending a lot of time together."

The Umbrella Academy star recalled that he was hanging out with Thirlby in her hotel room when things turned physical.

"She was about to start making lunch, when she looked directly at me and said point-blank, 'I'm really attracted to you,'" Page remembered. "'Uh, I'm really attracted to you, too.' At that we started sucking face. It was on. I had an all-encompassing desire for her, she made me want in a way that was new, hopeful."

He explained, "It was one of the first times someone would make me cum, the first time I would open up. And we started having sex all the time: her hotel room, in our trailers at work, once in a tiny, private room in a restaurant."

Page said the co-stars thought they were being "subtle" about their romance, and he wasn't sure if his mom Martha Phillpotts—who was staying in his two-bedroom suite during filming—"suspected" anything.

"She probably just thought Olivia and I had become fast pals," he wrote. "Which was true. But still, I kept it hidden. Olivia came to my suite maybe once."

After spending time with Thirlby and exploring the Canadian city with friends, Page said he felt truly "reinvigorated" by his experience on Juno. "We said our sad goodbyes in a curling rink, a very Canadian wrap party," he shared. "My heart hurt as I traveled home."

Thirlby, now 36, came out as bisexual in 2011, telling Brooklyn Magazine, "I am not 100% straight… I'm so lucky to have a job where it's okay for me not to be in the closet." She married Jacques Pienaar in 2014.

That same year, Page came out as gay, before sharing publicly in 2020 that he's transgender. His memoir Pageboy is available now.

E! News reached out to Thirlby for comment but hasn't heard back.