The final moments of X-Men: Days of Future Past is a heartwarming, geek-out worthy sequence in which it is revealed that the X-Men timeline has been altered drastically and previously deceased characters, namely Cyclops and Jean Grey, have been brought back to life. When Vulture asked producer/screenwriter Simon Kinberg if the character rebirths were always planned, he responded: "I went back recently — like two days ago, because I've been in Baton Rouge and my brain's been in Fantastic Four — I put my brain back into Days of Future Past, and I looked at my original outline for the movie, which was dated exactly two years before we're premiering the movie: May 10th, 2012. The original outline, the first thing anyone read — the studio, the producers, anyone — it was something me and Matthew Vaughan worked on together. In that original outline, the characters that come back at the end of this movie came back. For me, the fun of this movie from when I said, 'We should do Days of Future Past,' was literally the scene of changing the future and Jean is going to come back and Jean and Wolverine are going to have a reunion. Mainly because I carry such guilt over X-Men: [The Last Stand]. The way we killed Jean in X3 haunts me because I love the Dark Phoenix saga so much."
Does he have any regrets about X-Men: The Last Stand? "It was a missed opportunity," he replied. "That and Days of Future Past are my 2 favorite X-Men runs. So, I feel like what we did on 'Dark Phoenix' was not make it the 'Dark Phoenix' movie. We made 'The Cure' movie with 'Dark Phoenix' as a subplot. If I was going to do it now, and if we were doing it now because comic book movies are different, the darkness and the drama of that story would be differently supported." He then recalled killing off Cyclops, played by James Marsden, in X-Men: The Last Stand. "People love Cyclops in the comics. Jimmy does an admirable job. Not to make this about X3, but in X3 we did what we did with Cyclops partly because had a schedule nightmare. He was making, ironically, Superman with Bryan. We had a week with him and we needed to make a decision to integrate him into the film then lose him."
On teasing the audience with mutant deaths in the opening X-Men: Days of Future Past sequence and later in the film, Simon Kinberg says there was definitely a line. "The thing that's tricky about that is, you don't want the audience to think, 'Every time someone dies it's a trick, so I don't want to emotionally invest in them anymore.' But we wanted to establish Kitty's power as we've defined it, both visually and dramatically, as opposed to just verbally. And there's something radical about starting a movie with a bunch of characters and seeing how badass the villains, the Sentinels, are." On Wolverine surviving drowning, Kinberg says, "That was part of the challenge. Bryan and I asked, 'How do you actually put Wolverine in real jeopardy?' Not just getting shot or blown up. Bryan had some science for how the lungs would rebuild themselves."
On the brief moment in the opening sequence of Days of Future Past where Iceman and Kitty Pryde make eye contact and what it means for the love triangle they had with Rogue in The Last Stand, Kinberg says: "It's a really astute catch because that's absolutely the intention. That is its own complicated thing because we shot a sequence with Rogue [for Days of Future Past]. But Rogue in that future, where Kitty and Bobby are living as refugees, is gone. She's gone from their lives. Even in the version we shot with Rogue, she was gone from their lives. And in the darkness and sadness of losing so many of their friends, and specifically Rogue, Bobby and Kitty ended up together. That's totally the intention of that look. We debated that look — would it confuse audiences? Would it look like a plan they're conceiving? It's just meant to be an emotional character moment between them. It's a subtle read. And the idea is that, once we've reset the world with the events of 1973, there was never a world in which their friends and Rogue were killed. So he never strayed from Rogue. He stayed with her as plotted in the original movies." He continued, "Shit like that, in the whole movie with all the time travel stuff — what would have happened, what did happen, what changed — there's a rationale behind pretty much everything in the movie. We talked about a ton. I've never talked so much about a movie while making it."
About the scene where Quicksilver, played by Evan Peters, tells Magneto his mother knew a guy with his metal-controlling power, Simon Kinberg, laughing, says it was a little tease. "You know the intention of that tease. Hardcore fans will know. Some people who get that Magneto is a bit of a playboy will know." And finally, in the final shot in X-Men: Days of Future Past before the credits roll it is revealed that Stryker is actually Mystique. "We really wanted to do something subtle with Stryker in this movie," he said. "We wanted it to be the beginning of the origin of him. He's in the shadows most of this film. In some ways, Stryker was included in order to trigger something for Wolverine. How would it impact Wolverine, going back in time and seeing this guy who is going to manipulate him in the future. That was just interesting. Stryker's been interesting in the books and the Brian Cox version was fantastic. But the last moment in the movie with the Mystique reveal… there's for sure more to that. As we follow the characters in to X-Men: Apocalypse, we have to address that and make it a real thing."