'Twinless' director James Sweeney was hesitant to talk about his sex scene with Dylan O'Brien. Then it leaked online.

The buzz around Twinless out of the 2025 Sundance Film Festival was so intense, the film had to be pulled from the festival’s exclusive streaming website because scenes leaked on TikTok and X.

The movie, which won the festival’s top audience award, follows two men who meet at a support group for people who have lost a twin. It stars James Sweeney, who also wrote and directed the movie, and Dylan O’Brien, who won the festival’s special jury award for acting for his dual role as twins.

Sweeney spoke to Yahoo Entertainment on the ground at Sundance, where the film was creating buzz and selling out screenings but hadn’t been plagued by piracy yet.

Growing up in an era when Lindsay Lohan’s Parent Trap and several movies featuring the Olsen twins dominated pop culture, Sweeney developed a fascination with that extra-close sibling dynamic. He dated an identical twin, and when he started thinking about what it would be like to lose a twin, he thought it was the “saddest thing I’ve ever heard.”

“Honestly, if I think about it too much, I will cry. It’s such a profound bond,” he said.

Sweeney, who also wrote, directed and starred in the 2019 rom-com Straight Up, said there were years when “everybody in town passed on” Twinless. O’Brien signed on early in the process, though, and “never doubted it.”

Sweeney was hesitant to give much away about O’Brien’s role but said the actor filmed each of his twin character scenes separately across different months. He plays both Roman, who Sweeney’s character Dennis bonds with in a support group, and Roman’s deceased twin, Rocky.

As a former child actor who starred in the popular Teen Wolf series and Maze Runner movies but has since become a Sundance regular, O’Brien has a dedicated online fanbase that broke past the film’s secretive festival promotion and may have contributed toward the leak of his Twinless scenes.

Lauren Graham plays Roman and Rocky’s mom, who spends much of the film grieving. Sweeney, a big Gilmore Girls fan, said he was “reticent” about reaching out to her at first.

“I was like, ‘Is she going to think I’m a lunatic?’” he joked. “I think she’s such a wonderful actress ... and I have so much respect for her.”

On the red carpet for the Twinless premiere, Graham repeatedly spoke about how thrilled she was to be able to take on a darker role because she never gets opportunities like this.

Another nugget from his childhood that Sweeney put into the movie was a reference to the life simulator computer game The Sims. Dennis and Roman dress as the video game characters for a costume party.

“I’d lose days of my life to The Sims,” Sweeney said. “You get to build your own world. It ties into Dennis constructing these fantasies.”

Sweeney added that originally, the script called for a reference to a Nintendo game involving twins, but they couldn’t clear it after months of trying. It was a blessing in disguise, though, because so many people have fond childhood memories of playing The Sims, including O’Brien, who told Yahoo Entertainment on the Twinless red carpet that he loved cheating the game to get more money and deleting the bed out from under Sims who were getting naked.

“I was somebody who just really wanted to get promoted and focused too much on the skills and not enough on the relationships,” Sweeney said, laughing. “I feel like that’s something I need to explore in therapy.”

He was hesitant to talk about the sex scene in the movie, but less than a week after the interview, it leaked online. The scene involves Sweeney, who directed himself, and O’Brien.

“It helped that it was such a comfortable set. I think ultimately I had to shove down the personal, bodily, actorly insecurities and take control as a director,” he said. “This services the movie, and this is what I need to do, so I need to compartmentalize those emotions.”

At its premiere, Twinless drew a lot of laughs and made a lot of people physically cringe. There’s a twist Sweeney didn’t want to discuss because he wants the film to have “a full life” in theaters. He hopes people are “a lot more curious after they’ve seen it versus going into it.”

One thing he was eager to share, though, was that the film cast real-life twins as the background talent in support group scenes. Local casting agencies put out fliers seeking them out. Sweeney himself started seeing twins everywhere.

“I had just come back from scouting a location ... to the Airbnb where I was staying, and I was looking around, and I thought, ‘Are those twins?’” he said, then walked up to the pair. “I was like, ‘Hi, excuse me, are you twins? ... I’m directing a movie and we’re looking for twins.’”

They said they already knew about him and his movie — they’d seen the flier. One was too busy to film, but the other ended up joining the cast.

Ever guarded, Sweeney wouldn’t say what’s next for him.

“It’s not real until it’s happening and I don’t want to jinx it,” he said. “I want to do another rom-com, and I’d love to do a legal thriller drama. I think I’d be a lawyer in a different life. ... Maybe it’s not even directing. Maybe I’ll just play a lawyer on [Law & Order:] SVU.”

Twinless has not yet announced plans for distribution.