Separate Marvel properties are the only thing standing in the way of a MASSIVE Marvel crossover event.
Fans have been contemplating a crossover event between the Avengers and the X-Men since Iron Man (2008) premiered. Before that, the X-Men franchise had made their presence known in the cinematic world as well, already hosting up to three installments within the X-Men cinematic universe. And once both Marvel properties received their cinematic adaptations, the fanboy talk didn't stop, in regards to the potential crossover between the Avengers and the X-Men. Before proceeding with why these two separate Marvel properties are destined to be combined on-screen, we need to restate the known facts of each Marvel property owned by separate entities.
For one, we know that all of the characters that fall under the mutant category or anyone directly connected to the X-Men are owned by 20th Century Fox. Fox had ownership of several other Marvel properties before their inaction to use those properties resulted in properties like Daredevil, Ghost Rider, and Blade reverting back to the general base of Marvel, which is owned by Disney.
Aside from the X-Men properties within the Marvel universe, there's also the general array of characters based around the Avengers. Those property rights are owned by Disney and the subsidized Marvel.
Seeing is how the X-Men and the Avengers are owned by two separate entities, it places the potential for a crossover event in an unlikely state. As well as 20th Century Fox not willing to share creative use of the X-Men with the Marvel Cinematic Universe. The argument could be made as to why the MCU' (Marvel Cinematic Universe) doesn't forgo their cinematic universe's base to allow their characters to jump into the cinematic X-Men universe. But the long-standing MCU' wouldn't be able to find a plausible place to exist in the X-Men universe. Most of the heroes and villains of the MCU' have been established in known societies of the world, while having them appear in the world of the X-Men where enhanced superheroes and villains are scarce wouldn't place them in a believable capacity. The only reasonable crossover for the two would be to have the X-Men and mutantkind altogether to appear in the MCU' due to a specific event taking place, causing the mutants of the X-Men universe to fall into the Marvel Cinematic Universe unexpectedly. That event may be caused by a particular individual in the MCU' who has the power to alter reality, and was just recently introduced to the MCU' in Avengers: Age of Ultron.
Scarlet Witch has the power to alter reality and change the facts of the universe. We've only seen simple displays of her abilities in her two on-screen appearances, but she may be developing her powers further to change reality on every level. The comic-book counterpart to Wanda Maximoff a.k.a. Scarlet Witch has her altering reality on more than one occasion, wherein she's brought mutants into the existing Marvel universe, as well as depowering all of mutantkind. She has the ability to alter the long-standing facts of the Marvel Cinematic Universe, including the existence of the X-Men. Her powers may be the key to introducing the X-Men to the MCU'.
Now that's all speculative for the moment. But aside from Scarlet Witch's role in the MCU' creating the potential crossover event for the X-Men and the Avengers to participate in, there may have been some subtle Easter Eggs dropped in both X-Men films and MCU' films which proves the intent to combine all Marvel properties in one cinematic feature, eventually. Here are the biggest hints at discovering why the X-Men and the Avengers will receive a crossover event before Avengers: Infinity War.
1. Crashed Helicarrier in Deadpool
The ending scenes of Deadpool (2015) had Wade Wilson a.k.a. Deadpool facing off against his arch-enemy, Francis a.k.a. Ajax. The fight concluded spectacularly, as one would expect of two super high leveled mutants getting into a fist-fight. Apart from their fight sequence, what was most interesting in this scene is the setting of their fight. The scene all takes place on top of a destroyed helicarrier. The helicarriers are mostly known in the MCU' as aircrafts for SHIELD. But the inclusion of the destroyed helicarrier in Deadpool could be linking the events of Captain America: Winter Soldier to the X-Men universe. There's no direct connection made but the nature of the crashed helicarrier all but says that the events of Deadpool (2015) take place around the same time as Captain America: Winter Soldier, or a bit after. From the destroyed nature of the helicarrier, the scene may be taking place immediately after Captain America: Winter Soldier, before a clean-up crew can come in. That being said, the inclusion of the destroyed helicarrier in Deadpool is connecting the X-Men universe to the MCU' by intertwining a well known device used in the MCU' as a set piece in the X-Men cinematic universe.
2. Wanda Maximoff never shows up in X-Men: Days of Future Past.
Quicksilver's mysterious little sister of Days of Future Past never appears. Before X-Men: Days of Future Past debuted, there were promotional images of Evan Peters as Peter Maximoff making the rounds, but he wasn't alone in the images. He can be seen, holding his baby sister, Wanda a.k.a. Scarlet Witch. The mentioned promotional image was the only one shown of Wanda Maximoff in X-Men: Days of Future Past. Her character was completely cut from the film, and for good reason. We did see a glimpse of Wanda sitting in the background of the one of the scenes in X-Men: Days of Future Past but she's never given an introduction or even a single line.
Removing Wanda Maximoff from the X-Men universe isn't that big of a deal, but when the Maximoff twins of the X-Men universe and the MCU' are both missing their duo counterpart, it says much more. Especially when such an influential character like Wanda Maximoff disappears from the X-Men universe, there's likely a good reason for it. The likeliest reasoning behind the removal of Wanda Maximoff in Days of Future Past may have been attributed to the Scarlet Witch of the MCU' being the prominent, and only Wanda Maximoff present, once the world of the Avengers and X-Men crossover.
3. Pietro Maximoff of the MCU' is dead, while his X-Men universe counterpart is still around.
Quicksilver of the MCU' is dead. Along with the mysterious dissappearance of Wanda Maximoff in X-Men: Days of Future Past, we also have Pietro a.k.a. Quicksilver of the MCU' dying during Avengers: Age of Ultron. And It doesn't look like Pietro is being brought back to life anytime soon either. His death may be due to another Quicksilver being present in the MCU' some time soon to take his place.
Seeing is how Wanda Maximoff of the X-Men universe is nowhere to be seen, and Pietro Maximoff of the MCU' has recently exited from the universe, it's possible that the remaining Maximoff counterparts will find each other when the two universes crossover. That being said, Wanda Maximoff (Elizabeth Olsen) could be the catalyst to the universes/realities changing, resulting in a different version of her brother arriving into the MCU', along with more mutants like the X-Men. Those theories are speculative for the moment. But we can confirm that each respective cinematic universe only has one part of the Maximoff twins remaining active in their universe, and the two universes may be united with the Maximoffs finding one another.
4. Trailer for Doctor Strange (2016) introduces alternate realities.
The Doctor Strange trailer implicates Stephen Strange in altering realities, and venturing into unknown worlds. And the biggest tidbit of information that provides evidence to back up the theory of the X-Men universe and the MCU' crossing over is the dialogue within the trailer for Doctor Strange (2016). Within the trailer, we can hear the Ancient One (Tilda Swinton) explaining the nature of the universe to Stephen Strange. And she makes the biggest statement by telling Stephen Strange of the other potential realities which exist alongside one another. That in itself is enough to back up the theory of the X-Men dropping into the MCU'.
The differing realities won't integrate the X-men all at one time, or even in Doctor Strange later this year. But the possibility of Stephen Strange encountering different realities makes the idea quite plausible, when considering Stephen Strange dropping into a reality where the X-Men exist in everyday society. We just witnessed a world that recognizes mutants in the public eye, during X-Men: Apocalypse. In that scenario, even a small glimpse of Stephen Strange within the X-Men universe would be enough to provide the basis for a crossover event to occur.
5. Renaming Avengers: Infinity War may be due to the X-Men having a pivotal role in the film.
The Avengers Infinity War title has been scrapped for Avengers 3 and 4, leaving an open sub-title for The Avengers 3 film to include a tagline for the new introduction of the X-Men to the MCU. That theory is speculative, but we could see a new title revealed for the slated, Avengers 3 and 4 which implicates the involvement of the X-Men in the MCU'. And it is a stretch to go so far, just from the implications of the Russo Brothers altering the title to Avengers: Infinity War Part 1 and Part 2. However, a new deal may be in the works to share all Marvel properties. Wherein the Russo Brothers are mandated to change the title of their next Avengers team-up film to something that would relate to the X-Men appearing alongside of them.
What do you think? Are the Avengers and the X-Men being set up to crossover in The Avengers 3 and Avengers 4? And could a deal already be in the works for the separate Marvel properties to crossover sooner than later? Have any thoughts, leave them in the comments section below.