Deadpool may look on the surface like it's fairly stand-alone, whether it's the zany tone, the R-Rated edge, or just the fact that only one X-Man - and a slightly out there one in Colossus - has a major role in the film. Not so, say writers Rhett Reese and Paul Wernick, who told Collider that he absolutely exists in the same universe, and will eventually cross into it in a more significant way.
"We are part of the X universe, and that is important," Reese said. "Simon Kinberg is our producer and he kind of minds the store in regards to the X universe, so we are fitting into the larger timeline, we need to recognize that. I mean, we have things like the Blackbirds in the movie, we reference Professor X in the movie. So Deadpool is very much of that world and I think sooner or later we’ll cross over into that world."
Of course, the writer cautioned that it might be more in the "later" column, and that they actually hope to do a solo sequel before moving him into interacting with an X-Men style team.
"I mean, we’re not sure when that would be. Probably, if I’d have to guess, we would do a standalone sequel before he entered the actual ensemble movies, but I think at some point it will cross over and it needs to fit," Reese said.
Much of the crossover in this film will be handled by Colossus, simply by being present, but Deadpool does "joke about being in an ensemble movie" in the film, Wernick teased.