WARNING! The following contains spoilers for Deadpool 2.
We live in an age of crossovers and cinematic universes, spin-offs and team-ups, where the biggest franchises are all connected to the point that audiences expect them to be. This is the product of Marvel's wildly successful shared cinematic universe -- a model that other studios have tried to copy to varying success with comic book movies and other properties. Thus we now expect all of our big screen superheroes to intersect and collide, with heroes meeting and fighting alongside one another.
It is with this reality in mind that I imagine at some point Deadpool and the X-Force, seen in this past weekend's Deadpool 2, will be mixed with the core X-Men universe. Deadpool is probably the most popular mutant character in the movies right now, and he could be the face of the X-verse in the way Wolverine once was. Superhero universes are always moving towards bigger and grander team-ups, and combining the two halves of Fox's X-verse is an obvious way to accomplish that. Mixing the Deadpool and X-Men universes is a logical next step and likely a strong possibility. It is also a mistake.
Now there are some who will undoubtedly say, "What are you talking about, they are already in the same universe?" Well, sort of. Ostensibly Deadpool and Deadpool 2 take place in the X-Men franchise yes, yet there has been no crossover in any significant way. Wade Wilson never actually meets the core X-Men team, instead finding the X-Mansion with a population of Colossus and Negasonic Teenage Warhead and now Yukio. Deadpool actually makes fun of their absence and the current Deadpool has played no role in the X-Men films. Deadpool 2 did feature a fun cameo of Beast, Storm, Nightcrawler, Cyclops, Quicksilver and Professor X, but to me that no more makes Deadpool a true part of the core X-verse than his quips about 'Martha' make him a part of the DCEU. It's a fun little reference and joke for fans, not an inextricable link of connective tissue between the two.
There is also the matter of timelines. The current core X-Men team is operating decades before Deadpool takes place. Admittedly, Fox's X-Men universe has always played it fast and loose with continuity, taking a more laissez-faire approach and I'm sure that the Deadpool and X-Men timelines could be forced to work together like a kindergartner mashing two puzzle pieces with their fists to make them fit. But instead of going through some alternate universe timeline voodoo, better to leave them as they are, in the same universe in name only.
Now don't get me wrong, the idea of seeing Deadpool yucking it up opposite Quicksilver or making fun of boy scout Cyclops appeals to me as much as the next fan. And I must admit that seeing Deadpool break the fourth wall and having the X-Men either not hear him (a la Stewie in Family Guy) or ask who he's talking to would be funny, but for how long? And how enjoyable will Deadpool be in a PG-13 movie where we can't get him at 100%? Having him beeped out would be hilarious, but the jokes behind the beeps would still probably need to be tempered for younger audiences. There is the inherent problem with mixing the two; they would detract from one another, to the point that each is lesser for it.
Let's consider the next chapter in the mainline X-Men films, Dark Phoenix. Based on one of the most iconic storylines in all of comics, it tells the tale of when Jean Grey is exposed to an extraterrestrial force of immense power and loses herself to it. The Phoenix saga is emotional and epic and tragic. Deadpool has his tender moments but would such a story really be elevated or improved by having the Merc cracking wise throughout, referencing the failed attempt at this story in X-Men: The Last Stand? I struggle to see how Deadpool works within the context of the kinds of stories the main X-Men films tackle.
On the opposite side of the spectrum, greater integration demands greater adherence to a defined continuity. Though continuity has never been a priority in the X-Men films, truly mixing the two halves would require it. Thus Deadpool is hamstrung in a way. I'm not convinced Deadpool could get away with disposing of canon characters like Deadpool 2 did with Shatterstar and or that it could play with timelines with Cable without running afoul of larger universe plans. Moreover, the absence of the X-Men in Deadpool's movies allows for Wade Wilson's adventures to be smaller, more personal and more character driven than greater crossover would permit. Logically, Professor X and the X-Men should have shown up to deal with an escaped Juggernaut, but they didn't, allowing for lesser-known characters to step up.
The benefit of the world Fox is building with Deadpool and X-Force is that it can operate independently and still have big events. Josh Brolin's Cable is awesome and Zazie Beetz's Domino is a revelation. Future Deadpool and X-Force films already have all they need to deliver great team-up movies that are fresh and entertaining without needing the main X-Men. This is not to say that Deadpool films should pretend the X-Men don't exist, just that they work best as they are now, with Deadpool operating within the context of the X-verse but independent from it, not unlike the relationship between the MCU's TV shows and its films.
I would be remiss if I didn't address the elephant in the room of the looming Disney/Fox deal. Should it actually go through, I don't think it's a stretch to say that a large portion of comic book movie fans are itching to see the X-Men opposite the characters of the MCU. That would likely require the X-Men to be rebooted. But we don't want Deadpool, which is working so well, rebooted. And thus for many of us to have the X-Men we want, Deadpool must stand apart. Rob Liefeld has said that Deadpool should only be in the MCU if Ryan Reynolds calls the shots, which we know is unlikely if the character is in the MCU proper. Besides, if it comes down to a choice between a Disney-neutered Deadpool in the MCU or the mouthy merc operating in his own pocket universe, the choice is no choice at all.
Deadpool works best when he is unfettered from the burdens of ratings, continuity or universe-building, when the filmmakers and talent can truly run wild with the character. As the two halves currently stand, keeping Deadpool and the core X-Men films at arms length allows for a brighter future for each, where Deadpool can still be Deadpool.