Carter called star David Duchovny over to a laptop computer to watch a fan-made video on YouTube. It was a montage of scenes from the old "X-Files" show set to Sarah McLachlan's forlorn "When She Loved Me." ¶ "It was intensely romantic and it almost brought tears to my eyes," Duchovny recalled. "It really did. And it reminded me that we have at the core of 'The X-Files' this very powerful relationship. We have to honor that and not shy away from the sentimentality of the fans or of the relationship itself. When we were doing the show, Gillian [Anderson] and I had got tired of it. And we wanted to be ourselves outside of it. I remember struggling. But now I think, 'God, what a great love affair.' "

The film will acknowledge the time passage and even have a bit of fun with it, such as a scene early on in which Mulder and Scully, in a corridor at FBI headquarters, both glance purposely at the portrait of President Bush on the wall; the Clinton photographs from the 1990s are long gone.

Carter recalls getting together last October at his L.A. house with Duchovny and Anderson to read the script. The three hadn't been together in more than five years. "It was wonderful, surprisingly powerful. I hadn't expected to be so struck by the momentousness of that reunion -- actually I got very emotional."

Carter says Duchovny and Anderson's first day on set together was a scene in the FBI office. "It's funny, I think the first thing they did together on the TV series 16 years ago was in Mulder's office in the FBI -- that's a coincidence actually."