Deadpool & Wolverine’s official trailer has teased its heroes joining the MCU, but they may revisit the franchise’s most successful project first.

A shocking theory suggests that Phase 5’s upcoming Deadpool & Wolverine will revisit Marvel Studios’ most successful project while bringing Ryan Reynolds and Hugh Jackman’s titular Deadpool and Wolverine into the MCU. Deadpool & Wolverine was confirmed to be in development after Disney’s acquisition of 20th Century Fox in 2019, with Reynolds quickly announced to be returning, while Jackman joined him in September 2022. As two of Fox’s most popular X-Men characters, Deadpool and Wolverine are expected to make their hilarious and action-packed mark on the MCU in July 2024, but their adventure could be more wide-reaching than first thought.

Following a teaser trailer released in February, Deadpool & Wolverine’s first official trailer in April 2024 provided more insight into the multiversal journey for the Merc with a Mouth and the clawed X-Men member. While Deadpool is recruited by the Time Variance Authority, Deadpool himself seems to be calling on Wolverine for help, leading to the pair joining forces against Cassandra Nova. Deadpool & Wolverine’s trailer may also tease the pair officially joining the MCU, as they can be seen jumping through a portal that appears to have been created by one of the MCU’s Masters of the Mystic Arts.

Deadpool & Wolverine Trailer Theory Posits They’ll Join Avengers: Endgame

Since the release of Deadpool & Wolverine’s official trailer, many theories have arisen questioning where the portal could lead. One of the most popular theories surprisingly suggests that Deadpool and Wolverine could be jumping through the portal to join the MCU’s heroes in the final battle of Avengers: Endgame. During 2019’s epic crossover event, Doctor Strange and the Masters of the Mystic Arts opened portals which allowed practically every MCU hero to join the fight against the Mad Titan Thanos, and while Deadpool and Wolverine weren’t included in this roster at the time, their Phase 5 debut could change things.

How Deadpool & Wolverine Could Pull Off Revisiting Avengers: Endgame

Of course, during production of Avengers: Endgame, Marvel Studios didn’t have the film rights to Deadpool, Wolverine, or any number of other X-Men heroes. This meant they couldn’t be included in the final battle against Thanos, though the line-up of Endgame’s final act was impressive nevertheless, featuring the majority of the MCU’s heroes. Even so, Deadpool & Wolverine could simply edit the titular heroes into the final battle of Avengers: Endgame, allowing them to help some of the MCU’s most iconic past heroes in defeating the Mad Titan, and potentially even witnessing Tony Stark’s heartbreaking sacrifice that saved the universe.

If this theory turns out to be true, it may make more sense for Deadpool and Wolverine to show up briefly during Avengers: Endgame’s final battle before deciding to make their exit and leave the MCU’s past heroes to it. On the other hand, Marvel Comics’ Deadpool’s Secret Secret Wars in 2015 retconned the Merc with a Mouth into the original 1984 Secret Wars storyline, which took place six years before Deadpool debuted. This story saw Deadpool operating in Marvel Comics’ original Secret Wars, which could be repeated in live-action with Deadpool and Wolverine’s inclusion in Avengers: Endgame’s final battle.

2015’s Deadpool’s Secret Secret Wars saw Deadpool have a major role in Marvel Comics’ 1984 Secret Wars event, but everyone’s memory of his involvement was wiped at the end of the storyline, meaning it was like he was never there.

Would Deadpool & Wolverine Revisiting Avengers: Endgame Ruin Marvel’s Biggest Movie?

Avengers: Endgame is, by far, Marvel Studios’ most successful project, achieving almost $2.8 billion at the global box office, which saw it become the highest-grossing movie of all time before Avatar’s re-release in 2021. A success of this magnitude is probably best being left untampered with, as Deadpool and Wolverine’s sudden retcon as being a part of Endgame’s final battle could run the risk of ruining the impact of the epic crossover event. Avengers: Endgame marked the perfect farewell to some of the MCU’s original heroes, so Deadpool and Wolverine perhaps shouldn’t get in the way of their emotional departures.

Conversely, it makes complete sense that Deadpool & Wolverine would revisit the biggest event in the MCU’s history, particularly when trying to give Deadpool and Wolverine the strongest MCU debuts possible. Having the pair of mutants operate in the background of Avengers: Endgame’s final battle, akin to Deadpool’s Secret Secret Wars, wouldn’t impact the overall storyline of Avengers: Endgame, and would actually help to establish stronger connections between Deadpool & Wolverine and the wider MCU. Deadpool & Wolverine has already been theorized to be revisiting events in the MCU’s history, and it would be difficult to avoid revisiting Avengers: Endgame.