Space. Time. Power. Reality. Mind. These Infinity Stones have driven 10 years of the Marvel Cinematic Universe to the glorious crossover explosion that is Avengers: Infinity War next month. But one of them has never made an appearance: the Soul Stone. But that’s not stopped the internet from coming up with some truly insane theories about it, though.
This is a very recent—and very silly theory—that primarily came from a leaked piece of promo art for Infinity War. All six Infinity Stones (usually referred to as gems in the comics, but Marvel really doesn’t want you to call them that anymore) got a poster of its own, with images of MCU heroes refracted in each of them. The orange Soul Stone’s power featured Tony right at the center of it... which some people believe means the stone is in Tony’s latest fancy Iron Man armor somehow. Some argue it’s in Tony’s arc reactor; some argue that maybe Tony is literally the stone himself. All because of this one poster, even though to be fair, the other posters’ Infinity Stones line up with the movies they’ve been featured in, so Captain America is in the Tessaract/Space Stone poster, Doctor Strange is on the Eye of Amagotto/Time Stone poster, etc.
That said, the Soul Stone has never been mentioned or even hinted at in the previous MCU films, and you’d think Tony would notice a big glowing magic rock had somehow attached itself to his armor. Also, Iron Man is the character the entire Marvel Cinematic Universe revolves around—of course he would be featured on the poster of the stone which s unaffiliated to another hero. Maybe he’ll get his hands on it in Infinity War at some point, but retroactively making it part of his life is an awful idea.
Hasbro recently unveiled its Avengers: Infinity War toys, and among them is a line of action figures that includes pieces that can be scanned with a recently released “Hero Vision” AR mask to get bonuses in a video game. Those pieces are shaped like the Infinity Stones, and whose toy includes the orange Soul Stone? None other than Dr. Banner himself, who’s... artistically welded it to a piece of cement with a metal bar sticking out of it like a mace.
As much as I would love the banal silliness of the Hulk finding the Soul Stone and then just sticking it into some rubble to create a weapon, this is probably not going to be our introduction to the final Infinity Stone. Let’s say it again for those at the back: Don’t believe every “spoiler” you see in a toyline.
Idris Elba’s all-seeing Asgardian may have lost the Rainbow Bridge he was guarding when Asgard fell in Thor: Rangarok, but according to one theory, his most important power might actually be within. Literally, because some fans believe Heimdall’s glowing eyeballs might actually be the Soul Stone, and the source of his ability to “see all the souls in the nine realms,” as he mentions in Thor: The Dark World. Plus, in another long-running—and equally delightfully silly—Infinity Stone fan theory, the first letter in the names of the objects that were secretly stones in the MCU spelled out each letter in Thanos’s name... mostly. The “H” and the Soul Stone were the only unaccounted letter and item, and apparently “Heimdall” was the best option to fill the blank they could find.
This ignores the fact that Heimdall, like the other Asgardians, is a godlike alien with innate special abilities, and there’s absolutely no reason to think his eyes are different than, say, Thor’s lightning powers. However, if his eyes are the Soul Stone... I really don’t want to watch Thanos retrieve it with the force you’d expect of the Mad Titan. Ew.
In the comics, Adam Warlock has had a long, important history with the Infinity Stones, and the Soul Stone in particular. This is why fans have long expected him to make an appearance in connection to the Soul Stone in Infinity War despite the fact we know we won’t be seeing Adam until Guardians of the Galaxy Vol. 3.
But that’s still not stopped people from assuming Adam’s cocoon—glimpsed in one of Guardians of the Galaxy Vol. 2's post-credit scenes—is actually housing the Soul Stone. This is literally only because part of the cocoon is glowing a bright, vaguely orange-ish light, so... yeah.
I have a soft spot for this recent theory (posited by ScreenRant, but more thoroughly explored by Charles Pulliam-Moore) thanks to its sublime silliness—the orange-hued planet we’ve seen in the Infinity War trailer as the backdrop for Thanos’ brawl with the Avengers secretly being the final stone. At first, it sounds ludicrous, because... well, it’s a planet, not a cosmic gem. But then the recent officially licensed Infinity War prelude comic dropped some hints that the stone could be an interstellar body, and Marvel’s current comic event Infinity Countdown has shown that the stones can grow to massive, planetoid sizes and don’t have to be gauntlet-scaled trinkets (click on Charles’ article above for the details). So... what if it really has been hiding in plain sight all this time?
Alas, it’s probably not going to be true, as we recently learned the planet is actually Titan, Thanos’ home. If he’s been researching and hunting Infinity Stones, he probably would’ve figured out his home was housing one and stuck it in his gauntlet long ago. Why wait to do it until the Avengers show up?
Before the release of Black Panther, one of the longest-running theories about the Soul Stone was that it was in Wakanda, and linked to the ancestral plane we’d seen in the trailers for the movie (or somehow helping to power Wakanda’s Vibranium-focused technological advances). Given Black Panther came out just a few months before Infinity War, and that we knew defending Wakanda in a huge battle would form a big part of Infinity War, it would’ve made sense to tease the final stone (something that definitely needs defending) there. But the movie is out now, is pretty dang amazing, and... has no Soul Stone.
That’s still not stopped people from believing that Wakanda houses the stone, even as we’ve learned that T’Challa’s kingdom plays a major role in Infinity War safeguarding another stone—the Mind Stone, located in the Vision’s forehead, which is why it comes under attack from Thanos’ forces. After all, one of Black Panther’s most famous traits in the comics is always to have a sneaky plan that surprises everyone, even his allies. Pulling out the Soul Stone he’s hidden away somewhere would certainly count as a surprise.
This is both wonderfully silly and also probably the Soul Stone theory that makes the most sense. The MCU’s version of the Infinity Gauntlet gives the Soul Stone prime place on the “front” of the glove, so it’s clearly of great importance. And Infinity War is already so wildly overstuffed with characters and setpieces that is could be argued that adding in the discovery of the last, most important stone on top of everything else the movie has to accomplish in two and a bit hours is just too much. So what if... it just wasn’t part of the movie?
After all, there is an Avengers 4 movie coming after Infinity War, no longer titled “Part 2” but still a deliberate continuation of what goes down in Infinity War. So why not just keep the Soul Stone shenanigans until then and keep fans waiting to find out what it is just a little bit longer? We could all use the time to come up with increasingly sillier theories about what the damn thing actually is.