Captain America and Black Widow are among the most famous duos of superheroes. Many fans of the genre have taken to their relationship over the decades. It's taken on various forms, including best friends and, at times, love interests.

In the Marvel Cinematic Universe, the duo is played by a pair of real-life BFFs in Chris Evans and Scarlett Johansson. It's possible, perhaps probably, that both are done with their on-screen roles in the MCU. But recently, there's been new speculation that that might not be the case. Beware of spoilers below for multiple MCU installments.

Theories emerge that they might be back for a Nomad movie

It should be noted that it's true that the Internet can be rife with baseless theories, even in some cases leading to dangerous results. Hopefully, that wouldn't be the case with Marvel theories, whether they're accurate or not.

ComicBook.com notes that a new theory involving Steve Rogers and Natasha Romanoff has come up. The alter egos of Captain America and Black Widow, portrayed by Evans and Johansson. It's based on a ton of circumstantial evidence, but it's not totally bizarre.

Fans have continued to mourn Steve and Natasha's "Endgame" destinations, which included Natasha sacrificing herself to save half the universe's population. By the time of "Infinity War," the two led a team of other superheroes living under the radar.

Before all that went down, each had to go on the run due to "Captain America: Civil War" events.

Many onlookers quickly drew parallels to a storyline in the comic books. Where Steve Rogers essentially goes rogue and takes the 'Nomad' moniker, shedding his identity as 'Captain America.' Thus far, it hasn't seemed like Marvel would pursue the similarities much further than that.

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New theorizing stems from a number of events

Some recent, separate events (along with some possible word-parsing) may indicate there's more to come. Likely starting with Marvel trademarking a title for a Nomad-based adaptation.

That was followed by specific reports surrounding Johansson and Evans. One was that Evans was close to a deal to return for a couple more MCU projects.

But that neither was expected to be a specific "Captain America" production. Then, there was the news that Johansson was working on a 'top secret' MCU project. But, despite its secret status, it was apparently known not to be specifically Black Widow-centered.

All things considered, it's not out of the question to wonder if something could be in the works, something that features Steve Rogers and Natasha Romanoff working without their traditional alter egos. It seems time will tell.

The popular real-life duo of Evans and Johansson was recently poised to star together again. This time, in another non-MCU project, as they've done before. But a scheduling conflict led to Johansson dropping out.

A potential Nomad project would most likely take place after 'Black Widow'

Even if a Nomad movie happened, it probably wouldn't change what happens to the character in "Endgame". Much to the chagrin of many. "Black Widow" also takes place following "Civil War". It includes a mid-credits scene that sets up Natasha reuniting with Steve, each having been in hiding. Chronologically, the possible 'Nomad' installment would probably come next.

A plot point featured heavily in other MCU projects. Including "Spider-Man: No Way Home" and the upcoming "Doctor Strange in the Multiverse of Madness." There is also the possibility of Marvel again utilizing the multiverse, which would open up numerous possibilities for storylines.