Warning! This article contains spoilers for The Fantastic Four: First Steps.

Thanks toThe Fantastic Four: First Steps, I am convinced that Doctor Doom will beAvengers: Doomsday’s main character. Theending ofThe Fantastic Four: First Stepsdid not do much to actively set upAvengers: Doomsday, with the team remaining in their contained universe after defeating Galactus.Fantastic Four: First Steps’post-credit scene, however, changed this.

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The scene massively teased the2026 Marvel movieby officially introducing Doom to the MCU multiverse. How exactlyAvengers: Doomsday’s storyis going to play out remains to be seen, butThe Fantastic Four: First Stepsprovided a fairly big foundation for some theories to be crafted.

One theory in particular links directly to the film’s post-credit scene and one ofThe Fantastic Four: First Steps' biggest characters. Stemming from this theory, I am more convinced than ever that Doctor Doom will be presented as the lead character ofAvengers: Doomsday.

Robert Downey Jr’s Tony Stark and Doctor Doom from 2005 Fantastic Four movie with the Avengers slightly blurry in the background

The Fantastic Four: First Steps Teases Doctor Doom’s Avengers: Doomsday Role

Doom’s Multiversal Plan Could Be Linked To A Fantastic Four Character

Firstly, it is worth exploring exactly what happened inThe Fantastic Four: First Steps' post-credit scene and how this has formed a specific Marvel theory based on theSecret Warscomic books. The scene shows Sue Storm reading to a now four-year-old Franklin Richards before leaving him on the couch to find his favorite book.

Upon returning,Sue sees a figure clad in a green cloak with a metal mask in its left hand kneeling in front of Franklin. Franklin reaches out to touch this person’s face before the scene cuts to black, and the message that The Fantastic Four will return inAvengers: Doomsdayflashes on screen. Of course, this figure is Doom himself.

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Given that this scene focused on a connection between Doom and Franklin Richards, I have a theory that the latter will be the MCU’s version of the Molecule Man. In the 2015Secret Warscomic book event, Doom teams up with Doctor Strange and the Molecule Man to stop incursions across the multiverse.

Eventually, Doom realizes he cannot save the multiverse and uses the Molecule Man’s power to create Battleworld, a combination of the last surviving dimensions.Avengers: Secret Wars’storyis likely set to include Battleworld, meaningAvengers: Doomsdaywill establish how this came to be. AfterTheFantastic Four: First Steps, I think Franklin has a part to play.

Franklin is a being of insane power in Marvel Comics, even having the ability to create universes.I think the MCU will combine this with the Molecule Man’s Marvel Comics abilities, revealing Franklin as the person Doom enlists to stop the multiversal incursions, explaining the somewhat intimate connection shown inThe Fantastic Four: First Steps’post-credit scene.

Doom Taking Franklin Could Make Him Avengers: Doomsday’s Main Character

Based On His Motivations In The Comic Books

If Doom does take Franklin, as the MCU’s Molecule Man, in an attempt to stop the incursions threatening the multiverse, it would make sense to have him asAvengers: Doomsday’s main character. InAvengers: Infinity War, the Russo Brothers described Thanos as that film’s main character, as it focused on his plight to save the universe from overcrowding, albeit with undesirable methods.

Doom wanting to stop multiversal incursions is a fairly noble intention, even if kidnapping Franklin and eventually ruling over Battleworld reinforces his villainous aspects.Avengers: Doomsdaycan focus intently on Doom by giving him the most screentime and outlining his attempts to save the multiverse, allowing him to be the lead of the film.

As Have The Russo Brothers

Thanks toAvengers: Infinity War, Marvel Studios has already proven that Doom being the lead character ofAvengers: Doomsdaycan work. Thanos received the most screen time inAvengers: Infinity War, and to great effect. This screen time allowed Thanos' motivations to be undoubtedly clear, all while making him just sympathetic enough to somewhat care about his plight.

If the Russo Brothers repeat this with Doctor Doom inAvengers: Doomsday, it could work just as well, if not better, as it did inAvengers: Infinity War…

In making him the film’s protagonist, though, enough time was also dedicated to making Thanos' villainy shine through, so that audiences still rooted for The Avengers. If the Russo Brothers repeat this with Doctor Doom inAvengers: Doomsday, it could work just as well as it did inAvengers: Infinity War.

Doom is also even more sympathetic in some ways than Thanos in the comics. If this is depicted well and the balance between reluctant hero and power-hungry villain is struck,Avengers: Doomsdayhaving Doom as its main character could work even better thanAvengers: Infinity War’s depiction of Thanos.

Doctor Doom Being The Main Character Of Avengers: Doomsday Makes RDJ’s Casting Better

Aiding A Somewhat Controversial Casting Choice

Robert Downey Jr.’s casting as Doctor Doom inAvengers: Doomsdayhas been controversial for several reasons. Many think that Marvel is just banking on the nostalgia of Iron Man with this casting choice, while others wanted someone of Romani descent to portray Doom due to his comic book heritage. Both are certainly valid complaints, but this main character theory could alleviate other worries.

After all, even those who have these complaints acknowledge that, purely from an acting perspective, Robert Downey Jr. is talented enough to portray a complex character like Doom. If Doom becomesAvengers: Doomsday’s main character, this acting talent will be on display, front and center. RDJ’s talents would be wasted on a smaller villain role, so a bigger one makes sense.

RDJ should be on screen as much as possible, especially after the big deal Marvel Studios made over his casting. If this theory fromThe Fantastic Four: First Stepscomes true and Doom spends the story ofAvengers: Doomsdaytrying to stop multiversal incursions, he would be the film’s main character and give RDJ time to shine.