writers Christopher Markus and Stephen McFeely the movie by revealing some new information regarding the twin Avengers movie. That includes their initial choice for the Soul Stone reveal.
Unlike the first five Infinity Stones, which previously made their respective appearances in other MCU movies, the Soul Stone remained a mystery until Infinity War. Apparently, the reason why it never factored in any prior films was because it's on an entirely new planet introduced in the same film - Thanos to give up Gamora just to wield the gem in Infinity War, and then Black Widow sacrificed herself so that the Avengers can get it for the time heist in Endgame. Apparently, there's a version of the narrative which would've revealed the gem in a more bizarre form.
The Russos took part in a watch party for Endgame and provided live commentary on the film where they shared new behind-the-scenes content, as well as scrapped ideas for both the movie and its predecessor, such as this weird notion to have Captain America as the Soul Stone. They didn't reveal more details about this, but added that the plan quickly fell apart. Check out their tweet below:
It's curious if this plan had something to do with Markus and McFeely wanting Red Skull to be back. According to the writers, bringing the character back was a big factor in them wanting to work for both Infinity War and Endgame since they introduced him in as Steve returned the stones to their respective places after the time heist.
With viewers' limited time with the Soul Stone, it's quite unclear how it actually works. Thanos only used it once in Avengers: Infinity War aside from executing the snap, and it was against Doctor Strange. The Sorcerer used various tricks during his one-on-one with the Mad Titan, including creating multiple copies of himself to confuse and contain the villain. It worked for a while, until the villain used the Soul Stone to decipher where the real Doctor Strange was. Meanwhile, unused concept art reveals Thanos using the same gem to suck the soul out of the heroes' physical bodies. In Avengers: Endgame, it wasn't utilized except for the two snaps from Smart Hulk and Tony Stark. It's curious if the MCU will ever bring the Soul or the rest of the Infinity Stone back as the move forward to Phase 4.
Source: Russo Brothers
