After 17 years of X-Men movies with as many as three different timelines, it has become quite a game to figure out where each new film belongs in the franchise lineup. Deadpool and it's upcoming sequel are no exception, but one theory brings a whole new depth to the already complex timeline situation.
Reddit user DToccs suggests that the Deadpool films and their world exist in the semi-fictionalized X-Men comics that exist within the real world of the X-Men and Wolverine films. In other words, Deadpool isn't real in the X-Men Cinematic Universe (XCU). He is a comic book character, perhaps loosely based on a mercenary who was real in their world at one time.
It doesn't take a whole lot of convincing to believe that Fox would have our favorite fourth-wall-breaking antihero's movie based on a comic book from another #XMen movie. It seems very Deadpool-esque when you think about it, and the theory makes sense when it is fleshed out.
While the world may have mostly forgotten the X-Men since the Westchester incident happened, comic books about their adventures are still around. In Logan, Laura is trying to get to Eden, which Logan believes is a fictional place once he discovers it in the pages of an X-Men comic she has. Logan makes it clear that the comics are an exaggeration of the real X-Men and their experiences as he angrily explains to Laura:
"It's a fantasy, kid. See that? Those are the names of the people who just made this [comic book]... They made this whole thing up. Okay? This whole... It happened once and they just turned it into a big fucking lie!"
This first introduced the idea of comics that are loosely based on the real-life heroes in the XCU. Apparently, the comics take a lot of liberties and have been in print for some time. What's to say Deadpool doesn't come from those, rather than the same reality as the X-Men themselves? This would explain some of the notable differences between the X-Men seen in #Deadpool and the ones in the original movies. According to DToccs:
The 'X-Men' comics in 'Logan' are based on real people and real events, although they have been twisted and changed to the point where people like Xavier and Logan, who lived the events, can't even recognize them in the comics. The X-Men of the comics have some major changes from the real ones; all of the them (including Wolverine) wear colourful uniforms [...]. In 'Deadpool', Colossus is distinctly different from the Colossus of the actual 'X-Men' movies in every way, but he does resemble his character shown in the comics.
The theory also tackles the significance of Nega Sonic Teenage Warhead's existence in Deadpool. Let's assume the film takes place in 2016. When the "Merc with a Mouth" goes to the X-Mansion seeking backup, it seems Xavier's school is fully operational and, seemingly filled with mutant youth like Nega Sonic Teenage Warhead. There is just one problem, though: It shouldn't be. Sure, the school may be open, but none of the students should be young mutants.
In Logan, which set in 2029, we learn that there have not been any new mutant births since 2004. Depending on how old Nega Sonic Teenage Warhead is intended to be in Deadpool, she and any other mutant kids at Xavier's may actually be too young to exist in the XCU, at least with the X-gene. She may, therefore, exist in the films as she does because she was a newly-created character for the comics that exist in Logan.
This theory is not without its faults, but it is plausible. If any #Marvel Comics character is capable of pulling off a movie based on a comic book seen in a movie based on another comic book, it is Deadpool. Perhaps Deadpool 2 will shed even more light on where in the X-Men universe the series takes place.
What is your favorite X-Men Cinematic Universe theory?