The story requests Michael Fassbender and James McAvoy made for Dark Phoenix

Dark Phoenix director Simon Kinberg has been associated with the X-Men film franchise since writing X-Men: The Last Stand back in 2006. But it’s actually the final X-men film to enter into its long canon (outside of New Mutants, whenever that actually comes out) before the mutants move to the MCU that will be his directorial debut. And it was the request of his superheroic cast that got him at the helm.

Listening to and working with that cast resulted in a script that includes plenty of new comic details requested by those who’ve been playing the characters a long time — certainly long enough to know what fresh elements the X-Men films need. Speaking to The Hollywood Reporter, Kinberg explained that the actors who became the X-Men in First Class were not only key to his directorial job, but intimately involved in developing parts of the script.

“We presumed the First Class core cast — [Michael] Fassbender, [James] McAvoy, Jennifer [Lawrence], and Nic [Hoult] —  were coming back for this film,” Kinberg said. “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.”

It wasn’t simply support, either. For one of the film’s biggest stars, it was a dealbreaker. “Jen said she wouldn’t come back for another movie unless I directed it,” Kinberg explained. After he was needed to step in on the set of Apocalypse, Kinberg was battle-tested and star-approved. It makes sense that he’d turn to his actors for story ideas as well.

Michael Fassbender has played Magneto since 2011. Eight years with a character is a lot of time to mull over their most interesting parts. “I knew Genosha was something Michael had wanted to explore,” Kinberg said. “He was a fan of comics even before getting involved in the films, and we'd never gotten to do it in the movies before, so when I was trying to come up with where geographically we would meet him, Genosha sprung to mind and it was something that interested him.” So when Dark Phoenix introduces the mutant paradise of Genosha to the X-canon? That’s all Fassbender.

His rival across the mutant-philosophy aisle also had some script input. Professor X portrayer James McAvoy wanted the wheelchair-riding telepath to explore his dark side. McAvoy and Kinberg “had talked in the past, not specifically about this movie, about the notion that there is an ego drive involved with this character, and a patriarchal side to a man who names a superhero team after the first letter of his last name.”

So how does that reflect Charles Xavier’s potential heel turn in Dark Phoenix? “There was something about that that was obviously benevolent and paternal,” Kinberg said, “and there was something about it that could tip into something that was a little patriarchal and domineering.” Professor X certainly doesn’t like making mistakes — and his relationship with power has been growing more and more complicated as this cycle of X-Men movies has approached its violent conclusion.

Dark Phoenix takes comic fans to new lands when it hits theaters on June 7.