Based on the stories and endings of the last two the MCU timeline during this period. As such, the bar is high, to say the least.

With these stakes being readily apparent, it's no surprise that so many theories have emerged about what the story of the MCU movie might look like. One especially interesting theory posits that an evil variant of Steve Rogers' Captain America will appear in the film - which looks like a stronger story decision for the MCU's next Avengers installment now, based on the events of the franchise's last two movies.

Having An Evil Steve Rogers In Avengers: Doomsday Would Already Make Sense Without The Context Of The Previous 2 MCU Movie's Endings

Given Robert Downey Jr is returning as a villain via his casting as Doctor Doom in Avengers: Doomsday, it would seem somewhat par for the course for Chris Evans to also return in a more antagonistic multiversal variant form. The concept of an evil Steve Rogers is one that has had some prominent exploration in the comics - most notably in recent history with the Secret Empire storyline which saw him brainwashed into believing he was and had always been a HYDRA sleeper agent - and bringing Evans back alongside Downey Jr would ensure Avengers: Doomsday feels like a huge event.

With the movie featuring returns from Fox X-Men actors and MCU characters from almost every corner of the franchise, it wouldn't seem out of place for a story reveal like this to take place in the fifth Avengers installment. This would also work as a way for the arguably biggest two MCU actors thus far to the proverbial torch on to the next era of the Avengers, adding a nice sense of succession in that can balance out the fact that, by the time Avengers: Doomsday debuts, it will have been 7 years since the last Avengers movie in the series released.

The Ending Of Captain America: Brave New World & Thunderbolts* Makes An Evil Steve Rogers Appearing In Doomsday Truly Perfect

Having an evil Steve Rogers variant emerge in Avengers: Doomsday would also tie in perfectly to the events and final points of both Captain America: Brave New World and Thunderbolts*. Crucially, the arcs of both the current Captain America Sam Wilson and US Agent John Walker would benefit from seeing and confronting a warped version of the original holder of the hero mantle, albeit in different ways.

Sam Wilson facing a variant of his old friend and ally would no doubt cement his ion to honor "his" Steve's memory and uphold the values the Captain America mantle represents, while also challenging him by showing an example of how different the main universe's Steve could have truly been. It's likely facing off against such a figure could also be what helps draw an end to whatever current tensions exist between Sam and Bucky following Sam suing the New Avengers in Thunderbolts* and the pair having a terse phonecall, since they'd be most impacted by this event.

Were the MCU to loosely adapt the Secret Empire storyline here, it would also allow Bucky and Sam to potentially free this version of Captain America from his brainwashing, allowing them to team up in order to "save" a different version of their mutual friend.

On a similar note, John Walker being confronted with an iteration of Captain America that may be a little more similar to the version he was during his time in the mantle could serve as something of a turning point for him. Thunderbolts* depicts Walker as someone capable of genuine heroism, but also as someone who's bitter and haunted by his past misdeeds, and struggling with the reality of his situation. As such, giving him the chance to confront a symbol of these issues could be conductive to continuing the redemption arc Thunderbolts* suggests is in place.

The New Avengers & Main Avengers ing Together In Avengers: Doomsday Could Work Even Better If The Evil Captain America Theory Comes True

Captain America: Brave New World ending with Sam Wilson deciding he's getting an Avengers roster together - and the Thunderbolts* ending closing with the creation of the New Avengers - sets up a tense scenario for Avengers: Doomsday, which is confirmed to have of both teams. Since it's already established that Sam is understandably not pleased that Valentina has infringed on the Avengers name to create her own team of super-soldiers and assassins, it seems more likely than not that Avengers: Doomsday will explore these tensions during whatever plot ultimately unfolds.

Facing off against Doctor Doom looks set to bring these teams together - if only for the practical motivation of having more numbers to fight with - but pitting them against an evil Captain America would also prove the perfect motivation for the groups putting their differences aside. While the bonds these characters have to Steve range from being his best friend to Red Guardian's decidedly complicated feelings about Rogers, it's easy to see how all would be unsettled by seeing an iteration of the figure who holds the opposite values of their own, and how this could galvanize them into action.

Since Chris Evans already returned after the main Steve Rogers' ending for his cameo as the Human Torch in Deadpool & Wolverine, him appearing again seems viable for the franchise. While the actor did describe himself as "happily retired" regarding the MCU (per Esquire), it's not impossible to imagine him being willing to return once more, especially since the franchise has previously had actors like Andrew Garfield and Dafne Keen deny they were returning in the MCU right before they did. With all this in mind, seeing whether the Avengers: Doomsday theory does in fact come true makes the movie all the more of a must-watch.