Dark Phoenix, the latest X-Men film, is slated to wind up the long-running saga, rounding off over two decades of films with an epic ending that will once again tackle one of Marvel Comics’ most famous themes. But it was only until writer and producer Simon Kinberg agreed to take over as director that everything came together.

After the box office failure of X-Men: Apocalypse in 2016, veteran producer and screenwriter Simon Kinberg was recruited to take over as director for a sequel. With Bryan Singer facing allegations of sexual misconduct behind the scenes, returning cast members Michael Fassbender, James McAvoy, Jennifer Lawrence, and Nicholas Hoult expressed their support for Kinberg taking over as director, with Lawrence listing Kinberg’s return as a major condition to reprise her role as Mystique.

Jennifer Lawrence, James McAvoy, Michael Fassbender, and Nicholas Hoult have lead the X-Men series since X-Men: First Class. After X-Men: Apocalypse, the performers signed commitments for three films, but it was uncertain if any of them would return for Dark Phoenix. All of them ultimately signed up for another ride, and although it was unknown what would happen, Kinberg had little doubt they’d return.

Simon Kinberg explained in an interview with The Hollywood Reporter that they had always prepared versions of the screenplay anticipating the performers to return. They had promised to return as long as he directed, so Kinberg knew they would.

“We presumed the First Class core cast — [Michael Fassbender, James McAvoy, Jennifer Lawrence, Nicholas Hoult] were coming back for this film,” Kinberg explained. “Part of the reason I presumed that was at the end of finishing X-Men: Apocalypse, when it was clear Bryan Singer was not going to direct the next movie, it was the actors that approached me about directing the next of the X-Men movies. Jennifer especially. Jen said she wouldn’t come back for another movie unless I directed it. So, I had a lot of support from them.”

Sophie Turner, a returning cast member, said she had an “unpleasant” experience working with Singer on Apocalypse. With Kinberg taking over as director, the cast members collaborated closely with him on the story for Dark Phoenix.

Eventually, everyone returns for one more hurrah. While this is the last X-Men film from Fox, it wasn’t always certain that this would be the case. The Disney-Fox merger seemed to put an end to the franchise, but Simon Kinberg claims that he went into it knowing that it would most likely be the last.

“I feel as though the notion of this being the last of this cycle of X-Men movies is tied for a lot of people, at least in the industry, to the Disney-Fox merger. In truth, when I sat down to write this movie, which was three years ago, I thought about it as the culmination of this cycle of X-Men movies.”

Kinberg noted that his new job as director didn’t affect his approach to the material, but it did broaden his horizons.

“The writing and the producing and now the directing, they are all different job titles, but I approach them all the same way…in all cases I am looking at it from, how do I tell the best possible story with the richest themes and the deepest, most resonant characters? Each of those jobs, I feel like that is my responsibility.”

The X-Men will eventually appear in the MCU.