Going into Avengers: Infinity War, there was a mystery surrounding the Soul Stone. In fact, throughout previous Marvel Cinematic Universe films, the Avengers had encountered the Power, Reality, Time, Space and Mind Stones in one form or another. However, the Soul Stone remained, after 18 films, unaccounted for. Infinity War would finally reveal that the Soul Stone was on a planet called Vormir, and that it was guarded by the Red Skull. In order to obtain it, one needed to sacrifice someone they loved, thus trading one soul for another.

Obtaining the Soul Stone was an important plot point in both Infinity War and Endgame, and it cost the lives of both Gamora and Natasha Romanoff. However, it turns out the Soul Stone wasn't always going to be on Vormir. In fact, during a Twitter watch party of Avengers: Endgame, directors Joe and Anthony Russo revealed that during the film's development phase they considered making Captain America the Soul Stone. But how would that have worked, exactly?

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Thanos holding the soul stone in Infinity War.

In the MCU, the Infinity Stones were established as small physical gems. Sure, some of them were hidden inside powerful artifacts, such as the Tesseract and the Aether, but they were still physical objects. This instantly makes us wonder how Steve Rogers could have been the Soul Stone. Would it have been hidden away inside him, or would he have been the physical embodiment of the Stone? There is actually precedent for the former scenario in the comic books -- only it happened after Avengers: Infinity War was filmed.

At the end of the 2018-2019 Infinity Wars event, Adam Warlock gave sentience to the Infinity Stones and sent them flying across the cosmos to find living hosts. As a result, two of the Infinity Stones -- the Time and Reality Stones -- bonded with humans on Earth. The powers of these respective stones was now theirs to master once they realized what had happened to them. Therefore, it's possible something similar could have happened to Steve Rogers without him ever knowing about it. The Soul Stone could have been drawn to him thanks to his pure heart, and bonded with him as a result.

But if that was the case, the question would then become when could this have happened? Would it have been before he became a super-soldier, or long after, when he woke up from the ice in the present day, for example? There's no way to know the plan that was discussed, but perhaps this twist could have connected Steve and the Red Skull even more, seeing as how the Skull would become the Soul Stone's guardian.

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But then, if that was the case, it means Thanos would have needed to kill yet another Avenger to gain an Infinity Stone. In fact, this is the exact situation that happens with Vision in Infinity War, and it would have likely been too repetitive to have it happen with Steve Rogers as well.

Theorizing about how Steve Rogers could have possibly been the Soul Stone leads to many questions, and these questions are likely why the Russo Brothers dropped the idea rather quickly. Besides, this revelation could have also taken away from Steve as a character, as fans would likely have questioned whether he was worthy of lifting Thor's hammer because of how good he is or only because of the Stone. So, now that it's all said and done, it's safe to say the Russos made the right call.

Directed by Joe and Anthony Russo, Avengers: Endgame stars Robert Downey Jr. as Iron Man, Chris Evans as Captain America, Mark Ruffalo as Bruce Banner, Chris Hemsworth as Thor, Scarlett Johansson as Black Widow, Jeremy Renner as Hawkeye, Brie Larson as Captain Marvel, Paul Rudd as Ant-Man, Don Cheadle as War Machine, Karen Gillan as Nebula, Danai Gurira as Okoye and Bradley Cooper as Rocket, with Gwyneth Paltrow Pepper Potts, Jon Favreau as Happy Hogan, Benedict Wong as Wong, Tessa Thompson as Valkyrie and Josh Brolin as Thanos. The film is available on Digital HD, Blu-ray and 4K UHD.

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