Editor's note: The below article contains major spoilers for the ending of Eternals.Eternals director Chloé Zhao said Harry Styles had been on her radar for years and was the only person on her mind when she conceived of introducing the character Eros in the Marvel Cinematic Universe. “I still can’t believe it happened,” she told Variety in a new interview.

Styles makes his Marvel debut in the mid-credits scene of Eternals—a surprise that was spoiled moments after the film’s premiere last month, before it had been officially released. The unfortunate leak aside, Zhao spoke at length about how she decided to bring Eros into the fold. She said:

“The idea of Eros and Harry came to me at the same time. It wasn’t like I created this character and I think about different people [to cast]. Seeing his career, where he’s going, what he’s representing, him as an individual — he’s very interesting, unique. And I thought that is Eros. That’s that character. He just happened to be Thanos’s brother. I had this whole thing made up in my head, what their backstory is. I just was very, very excited when Kevin [Feige, went], ‘Let’s do it.’”

Dunkirk-Harry-Styles
Image via Warner Bros.

RELATED: ‘Eternals’ Ending Explained: Where Do We Go From Here

After saving the world from destruction, Gemma Chan’s Sersi is suddenly pulled aside, along with Kumail Nanjiani’s Kingo and Bryan Tyree Henry’s Phastos, by lead Celestial Arishem. He tells the trio that they will be tried for having a hand in the death of an Eternal—Richard Madden’s Ikaris flies too close to the sun, and commits celestial suicide—and that the fate of humanity rests in the outcome of the trial.

Meanwhile, the other Eternals—Angelina Jolie’s Thena, Lauren Ridloff’s Makkari, and Barry Keoghan’s Druig—are concerned about their teammates. And that is when Pip the Troll (voiced by Patton Oswalt) announces the arrival of none other than Eros, the legendary galactic Lothario, played by Styles.

Zhao said that the former One Direction star, who has since transitioned to acting in addition to his solo career, didn’t take much convincing to jump aboard. “I think everyone loves working with Marvel,” she said. “He was game, yeah.” His scene, Zhao said, was shot in one day, with Styles arriving on set in a hoodie to stay under the radar.

But Eros isn’t the only new character that Zhao introduced via a post-credits scene in Eternals. Although the movie essentially opens with scenes involving Kit Harington's Dane Whitman, it isn’t until the final moments that Dane’s true identity is teased. As he finds himself falling for the allure of the Ebony Blade, it is made all but obvious that Dane is none other than the Black Knight. Zhao added:

“I was a big fan of that character. I thought he would be very interesting to have a human character also with his own complicated [history]. You can sense he doesn’t know what’s going on [with the Eternals], but there’s something special about him. It’s fun.”

Eagle-eyed (or eared?) fans were quick to notice that a voice that cautions Dane as he is about to touch the Ebony Blade belongs to none other than Mahershala Ali, who, of course, will play Blade in an upcoming Marvel movie. The voice cameo essentially serves as his debut in the MCU.

But Harington had no idea about this until three weeks before the premiere. He said:

“I knew the line that was being said, because it was said out loud and it was in the bit of script that I got. I only knew that was Mahershala’s voice just about three weeks ago. Chloé texted me saying that’s what they were doing. It really excited me, hearing that. He’s one of my favorite actors out there at the moment.”

Harington said that he isn’t quite sure what the future holds for Dane, but hinted in an interview with THR that there are “many different ways” that they could go with him. Eternals is currently playing in theaters.