Warning: SPOILERS for What If...? episode 1.

What If...? episode 1 teases how faster Tony Stark's Iron Man armors would have evolved had his father invented the HYDRA Stomper during the events of Captain America: The First Avenger. While the Marvel Cinematic Universe kicked off with Iron Man in 2008, it was built on an exhaustive history of superheroes and supervillains. However, it wasn't until the 2010s that heroes like Iron Man, Hulk, Thor, and Captain America truly become known to the world.

In the span of a little more than a decade, Tony Stark went from building the scrappy Iron Man Mark I armor in a cave to building the nanotech Mark LXXXV in the comfort of his home. His genius-level intellect is responsible for the bulk of his inventions, but he also received support from his deceased father in a crucial moment. In Iron Man 2, Tony was able to create a new element with the help of Howard Stark's archive footage, which allowed him to build a new arc reactor and revolutionize his Iron Man technology. What If...? episode 1 not only makes Peggy Carter the first successful super soldier but also rewrites Iron Man's entire MCU history.

Related: Where What If...? Episode 1 Fits Into The Marvel Timeline

Peggy's transformation into the super soldier Captain Carter in What If...? episode 1 doesn't discourage Steve Rogers from joining the battle against HYDRA. But since Steve wasn't transformed into Captain America, Howard Stark takes the initiative to build him the HYDRA Stomper - an "indestructible" suit of armor. This means that by the time Tony comes up with the idea to become a superhero, the Iron Man nanotech he uses in Avengers: Infinity War and Avengers: Endgame must be already outdated. The Iron Legion, Mark XLII's Micro-Repeaters, the Hulkbusters - all of these state-of-the-art advancements could seem ancient to this version of Tony Stark. Captain Carter's arrival at the present day at the end of What If...? episode 1 suggests that Howard Stark's Iron Man technology is somewhere out there, more advanced than ever.

Howard Stark in What If and Tony Stark's Starboost Mark 39 Armor

If such a seemingly inconsequential decision as staying in the room during Project Rebirth turned Peggy into the powerful Captain Carter, it's possible that Tony Stark's life is also completely different in the HYDRA Stomper's timeline. Perhaps an advanced Iron Man armor helped Tony avoid being kidnapped by the Ten Rings, preventing him from using his wealth and influence for good. In that same vein, it's possible that Stark Industries used the Iron Man technology for war, and Tony remained a warmongering businessman who only sold the armors. Perhaps Captain Carter's universe features a Tony Stark with such an advanced Iron Man technology that he was able to predict and prevent Loki's invasion and Thanos' snap before they happened, or maybe Tony succeeded in creating a version of Ultron that protected the world for him and didn't turn rogue.

The timeline changes in What If...? prove that the possibilities for alternate MCU stories are endless, but one thing is for sure: by inventing the first Iron Man armor in 1942, Howard Stark completely changed Iron Man. Whether this resulted in a positive or a negative outcome for the universe remains unknown. And if He Who Remains' description of time is to be trusted, Peggy Carter and Howard Stark were better off letting it take its course.

More: How What If...? Connects To Loki's Multiverse Ending Cliffhanger

Marvel's What If...? releases new episodes Wednesdays on Disney+.

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