A new fan theory suggests that Robert Downey Jr.’s transformation into Doctor Doom could be linked to the events of Captain America: Civil War.

After his concluding arc as Tony Stark displayed in Avengers: Endgame, when Robert Downey Jr. was announced to be playing the new Doctor Doom in the MCU, fans were nothing short of surprised and concerned. Since then, a lot of buzz has been surrounding how he could be brought back without ruining the legacy set by his former fan-favorite billionaire genius superhero.

Robert Downey Jr. | Credits: Image by nagi usano / Licensed under CC BY SA 2.0 / Wikimedia Commons.

That said, quite a few fan theories have been popping up about the same, each holding a different idea on how things could turn out for the actor and his new character. One of these theories perfectly connects the dots between both Iron Man and Doom, going all the way back to Captain America: Civil War to do so as it has Downey Jr do what Stark couldn’t do in the film.

Marvel theory suggests Civil War holds the key to how Robert Downey Jr. became Doctor Doom

As fans already know, it was basically Robert Downey Jr. who kickstarted the Marvel Cinematic Universe through Iron Man in 2008. Thus, bringing him back to the screens as a supervillain after putting his beloved character to rest in Avengers: Endgame sounds like something that could seriously taint his legacy as Tony Stark if not dealt with in the right way.

RDJ as Stark. | Credits: Iron Man 2 / Marvel Studios.

However, a fan theory seems to be proving a rather plausible story that not only connects the dots between Stark and Doom’s connection and their uncannily similar resemblance but also explains that it might as well have been Stark who went on to become Doom going further into the future. This goes back to the story displayed in Captain America: Civil War.

While the 2016 movie had the Avengers turning against each other due to their respective different beliefs about freedom and responsibility as the Accords tried to get them all under their control, it also pretty much served as a direct battle between Iron Man and Captain America. This was also emphasized through the film’s ending featuring the two furiously butting heads.

In the movie, the brutal battle that ensued between the two superheroes resulted in Chris Evans‘ Steve Rogers walking out alive with Tony deciding to lose to him as he ostensibly didn’t want to sacrifice his morals. But what if things took a different turn, and, instead of losing to him, Tony actually decided to kill Steve, pulling the fight in his favor?

Well, that’s what a new fan theory suggests. According to the theory (per Comic Basics), if Tony actually killed Steve back then, the Accords would have inevitably passed without dispute. But this would have, in turn, deeply crushed Tony, causing him to spiral into feelings of guilt, anger, and madness, with the emotional trauma transforming him into a bad guy.

Avengers: Civil War. | Credits: Marvel Studios.

Since he would blame himself for being responsible for Steve’s death, this emotional trauma could lead him to seek more power to prevent future tragedies, maybe even making him try to control the actions of superheroes and the world with the belief that it is only through absolute authority that he could prevent further chaos and calamity and actually protect people.

That said, this desire for more and more power – even if driven by guilt and a need to fix things – could eventually have him trying to control everything, even involving him wanting to exercise complete power and authority over powerful technology, governments, or even the fate of the entire planet.

This would, in turn, put him in a similar state to Doom, who holds the desire to rule to bring order and safety to the world.

Robert Downey Jr.’s previous words more or less back this fan theory

Robert Downey Jr. | Credits: @robertdowneyjr / IG.

While this theory seems plausible, it doesn’t directly set up Stark to become Doctor Doom, but only puts him in a position that would have him feeling the same things as the supervillain as he navigates through a desire for excessive control and complete authority. Nonetheless, one of Robert Downey Jr.’s old comments seems to back this theory up.

As fans must remember, back when the actor announced through his social media handle that he would be returning to the Marvel Cinematic Universe as Doom, he captioned the post as “Different mask, same task.” This could have potentially hinted that he would be doing the same thing, just under a different mask – to be more precise, perhaps, an “Iron Mask.”

All of this being said, this theory has it’s own pros and cons and ranks among all the other theories out there about what could possibly be in store for RDJ and his two polar opposite characters in the MCU. But this, of course, might as well be taken with a pinch of salt like all the others, until it finally gets seen what actually will be unfolding for the respective actor.

Avengers: Doomsday is set to hit the screens on May 1, 2026.