With Stranger Things resuming filming in October after pandemic-related setbacks, it’s impossible not to wonder what season 4's nine episodes have in store. 

Now over a year out from the season 3 finale, there’s been much time for theories regarding the show to percolate. From the return of characters long thought dead to radioactive fallout, fans have been nothing short of imaginative. But in a world marked by parallel dimensions and a single Steve Harrington (crazy, right?), nothing seems out of reach.

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Below, we break down all of our favorite theories regarding season 4 of the show. Be forewarned: spoilers abound.

Dr. Brenner is still alive…but with a twist

Theories about Dr. Brenner’s reappearance have been circulating since the show’s season 3 finale. Many were quick to believe that the “American” referenced in the end-credits scene alluded to Hopper’s survival. However, others pointed out that the Russians may have gotten their hands on the season 1 antagonist. This concept isn’t a far cry, considering the doubt that season 2 stirred up over his presumed death. Matthew Modine, the actor behind Dr. Brenner, has even voiced his support for this idea. 

But what if he doesn’t come back as we knew him in season 1? A theory posed by Reddit user dnowakjr suggests the possibility that the character could have been turned into a Demogorgon, perhaps through experiments by the Russians. If this theory pans out, we could expect to see a very bizarre villain in season 4.

Read more: See Mest vanish into the Upside Down in ‘Stranger Things’-inspired video

Eleven was poisoned by the Mind Flayer’s bite

It was never explained specifically why Eleven lost her powers in the season 3 finale. However, simple correlation would attribute it to the Mind Flayer’s bite. Reddit user JadiSabre has an interesting idea regarding the science behind this. Given what we’ve seen of Eleven’s backstory, it seems that her powers are a result of altered brain chemistry. The Mind Flayer, on the other hand, drives its human hosts to consume various chemicals. Is it possible that it was stirring up a toxic cocktail that could counteract Eleven’s altered state? It seems entirely plausible to us!

A new love interest for Steve?

With all the interest generated over Hopper’s survival, everyone’s favorite teenage babysitter has been pushed to the sidelines. Don’t worry: There appears to be continued action for Harrington in season 4 (if you catch our drift). Recent behind-the-scenes photos show Joe Keery, presumably in character, checking out a brand-new face. While we can’t confirm that this mystery girl is indeed a new love interest for Harrington, it seems likely given the swing and a miss he took for Robin in season 3.

Read more: See another sneak peek of ‘Stranger Things 4’ as filming resumes

The Wizard Of Oz parallels

The Wizard Of Oz theories sprung up with the first season 4 teaser in 2019. The cryptic glimpse featured the Upside Down with the tagline “We’re not in Hawkins anymore.” As Reddit user revolver_soul stresses, though, this isn’t the first Oz reference the showrunners have thrown at us. After all, Eleven was kept in the “Rainbow Room” in the Hawkins National Laboratory. And if you look closely in Suzie’s bedroom, you can spot a Wizard Of Oz poster on her wall. Coincidence? Maybe not. It’s possible that we could see Eleven’s storyline playing out similar to Dorothy’s as she’s swept off to a much more sinister place.

…Or maybe the Mind Flayer is Dorothy

Reddit user JoeRWM8 has a much different idea regarding the significance of the Oz reference. In this theory, it’s the Mind Flayer that gets swept away to the Emerald City. Or, well, wherever it’s gone. In fact, it’s possible that the events of season 3 didn't take place in the Hawkins Upside Down. The idea comes from the creature’s reference to itself and its captives as “we,” which is echoed by the teaser statement: “We aren’t in Hawkins anymore.” Whatever reason the Mind Flayer had for leaving Hawkins, it would have had to be more pressing than facing off against Eleven—and that’s a terrifying thought in itself.

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The reprise of the Demogorgon

What if Eleven never actually killed the Demogorgon in season 1 but instead sent it to the Russian Upside Down? Reddit user Daddy-Ch3ddar addresses this possibility, explaining that the Demogorgon shown after the season 3 finale credits may be familiar. According to this theory, the Russians captured the creature to weaponize it. The idea may be a stretch given that the Russian Demogorgon is white, not black. However, it’s plausible that the Demogorgon may have lost its pigment after its brush with death in Hawkins. We’re not sure what this would mean for the plot, but it'd be interesting to see play out.

Hopper has been brainwashed

It’s already been confirmed that Hopper survived the season 3 finale (whew). But what if the Hopper we see in season 4 isn’t the same? Given that he’s been reportedly imprisoned by the Russians, it’s totally possible that he’s been tortured or brainwashed. Reddit user Conor_mc7 poses the theory that Hopper may have no memory of Eleven going into the next season. As heartbreaking as this twist would be, it would be interesting to see Hopper take on the role of a villain.

Demogorgons…but make them radioactive

As it turns out, the timeline of the show puts it in a prime position to factor in the Chernobyl disaster. As Reddit user blank_U notes, season 3 takes place in 1985, just a year before the nuclear accident. Considering we’ve already established that some events in season 4 may take place in Russia, it’s not a far cry to presume we could see some historical influence here. The theory suggests the Soviet cover-up may provide the perfect backdrop for the season to transpire without the world gaining knowledge of the Upside Down.

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Eleven will be the next sacrifice

All right, this is the one we really didn’t want to acknowledge because it’s deeply painful. However, as a now-deleted Redditor points out, the whole series has built Eleven up to confront the Upside Down. Though we’d obviously like to see a happy ending for all, it’s entirely plausible that she dies in the process. This would be a full-circle moment, with her character both opening and closing the gate.

Eleven will be the next possessed

Perhaps even more devastating, it’s possible that we could see Eleven become the next villain of the show. This theory hinges on the Mind Flayer doing more than just taking Eleven’s powers with its bite. Redditor weedmonkey666 noticed that Eleven’s cut looks suspiciously like Billy’s after he got infected. And while we never see her get “filled” by monster goo like Will, the slug she pulls out of the wound appears to parallel the one he threw up at the end of season 1. Should Eleven regain her powers prior to the Mind Flayer’s possession, she'll make for the most powerful enemy we’ve seen yet. 

What are your favorite Stranger Things season 4 theories? Sound off in the comments below!