A popular fan theory about "Stranger Things" Season 4 claims Dustin is the reason why there are Russians in Hawkins and why they have access to a Demogorgon.

Dustin (Gaten Matarazzo) is being blamed for bringing the Russians to Hawkins, where they conducted experiments involving The Upside Down. This theory goes back to a scene from Season 2 when Dustin had a Demogorgon for a pet.

Fans may remember in "Stranger Things" Season 2 Episode 9, he and Steve (Joe Keery) put a dead Demodog in the freezer. The whereabouts of that creature were never revealed afterwards. The creature was also never mentioned in Season 3.

"Dustin and Steve put a dead Demodog in the fridge for a 'scientific experiment' later, this doesn't get mentioned in the rest of season 2 nor in season 3," Reddit user @butterdudies wrote, adding "In the scene after the credits, they show that the Russians have a full-grown Demodog."

The user claimed that perhaps the Russians got hold of the dead Demogorgon and revived it. This would explain why they have The Upside Down creature at their underground lab at Starcourt Mall in "Stranger Things" Season 3. With this said, @butterdudies believes that Dustin brought the Russians to Hawkins.

Another fan, on the other hand, suggested that the Russians retrieved the Demogorgon from The Upside Down. After all, they managed to open the dark place in Season 3.

It is unlikely that one dead Demogorgon can prompt a full Russian squad to open a secret lab in Hawkins. Likewise, it is unlikely that Dustin is to blame for their appearance in Hawkins. He only knows so much about The Upside Down.

There are theories that also point to Dr. Martin Brenner as the culprit. While some fans believe that Chief Jim Hopper is the American captive teased in the Season 3 end-credits scene, there are also those who think that Eleven's papa is the prisoner. This theory would make more sense since he knows more about The Upside Down. He could have tipped the Russians off about the dark place and about his former work at Hawkins Lab.

Moreover, Matthew Modine even hinted at his return in "Stranger Things" Season 4 as Dr. Brenner. He specifically teased at his return as the American captive.

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