How does Deadpool know the X-Men?
One of Deadpool's many fourth-wall-busting gags has our (anti-)hero joking that the film's budget isn't big enough for all the X-Men, but we do get to see Colossus and Negasonic Teenage Warhead. When they show up, it's obvious Deadpool and Professor X's team know each another. Whatever history the merc with a mouth has with his uncanny frenemies, it's left unspoken in the movie, presumably to be pieced together in future films. We have a feeling the X-Men tried asking Deadpool to—you know—stop bringing chaos and death everywhere he goes.
What can we expect to see in Deadpool 2?
As Marvel readers are aware, Wade Wilson has been around the comics since the early '90s. He's had countless adventures along the way—many of which would make a fine fit for the sequel. Director Tim Miller has already come out and said that the next movie will need to make use of Deadpool's on-again, off-again adversary/buddy, Cable. In terms of plot threads left dangling by Deadpool, we might look toward the shadowy figures inevitably lurking behind main villain Ajax—as well as any secrets they might be able to reveal regarding Deadpool's powers.
Is Deadpool a mutant?
For decades, mutants have been a cornerstone of the Marvel universe, but that's changed over the last decade or so (thanks, Scarlet Witch). Not to the point where we can expect to see any X-Men books being canceled, but the question of what exactly constitutes a mutant, or whether characters once called mutants actually fit the definition, has gotten hazier. In Deadpool, it's suggested that all humans have a latent X gene waiting to be activated (spoiler alert: the process isn't fun), which puts Wade somewhere between, say, Cyclops and Captain America.
Where does Deadpool fit in Marvel canon?
Thanks to the already-tangled state of the X-Men cinematic universe, this is a question that's almost impossible to answer. Deadpool was previously seen in X-Men Origins: Wolverine, but that movie took place in the early '70s, which doesn't work at all with the origin story we see in the present-day Deadpool. Wade Wilson is definitely aware of the X-Men (and their movies), but as for where the events depicted in this film connect to any of the other Marvel films…it might be best to just enjoy the mayhem and not to think too much about it.
Why does Deadpool go after Ajax, anyway?
Yes, Ajax is a pretty nasty guy, but even if he puts Wade through hell, the end result—a cure for his cancer—is exactly what he promised. Without being disfigured and tortured, Wade Wilson would be dead. Ajax ultimately ends up kidnapping Wade's girlfriend Vanessa, but that's after the whole "quest for revenge" thing has been set in motion. Again: maybe it's best not to think too much about it.
Will Vanessa become Copycat?
Deadpool comic fans know that Vanessa Carlysle is also a mutant—a shapeshifter dubbed Copycat. This side of her character is never seen in the movie, but if Morena Baccarin returns for the sequel, it would make a lot of sense to advance her story in that direction. She's kind of really good-looking though, so we don't want her to shapeshift.
Any cool cameos from the comics?
The short answer to this question is "maybe." Given the number of fun little asides and self-aware gags the filmmakers threw in, it's impossible to tell what will stick and what won't, but there's what seems to be a brief glimpse of the Marvel mutant known as Marrow at one point in the movie. More importantly, we also see Bob, who readers will recognize as the Hydra agent who's gotten himself roped into a number of comics adventures alongside Deadpool.
Could Deadpool cross over into other franchises?
Well, he obviously knows the X-Men, so providing Fox has worked the proper caveats into Ryan Reynolds' contract, there's no reason why we couldn't see him in any of the inevitable follow-ups to the upcoming X-Men: Apocalypse. More intriguingly, Deadpool has been floated as a part of a different X-franchise—X-Force. Originally a grittier overhaul of Marvel's New Mutants title, the team featured Deadpool at one point, and Cable is a regular member. Using an X-Force feature to establish their relationship—or a Deadpool and Cable movie to lead into X-Force—could give Fox a fresh blockbuster franchise to build on. It looks like Wade will have to order tacos for two.