The appearance of Chief Jim Hopper (David Harbour) in the recently released teaser for "Stranger Things" Season 4 supposedly hints that he has been brainwashed by the Russians for some nefarious reason.

Netflix released the teaser for the upcoming season and finally confirmed everyone's theory that Hopper is alive. Sadly, he is not back home in Hawkins, but he is in Russia as the American captive teased in Season 3.

It is not yet known how long the Russian soldiers have held Hopper prisoner. But his new look supposedly suggests that he has been in there long enough to be brainwashed. Fans pointed out that Hopper no longer has his long hair and beard. He is completely clean-shaven.

Outside of his bald hair, Hopper also had that strangely vacant expression on his face. The "Stranger Things" Season 4 teaser zoomed in on his face as he removed his cap and looked out into the distance.

"Did the Soviets brainwash Hopper or something? This trailer makes it look like Hopper is a man named Boris!" one fan asked on Twitter.

Fans fear that the Russians have brainwashed Hopper for some evil purpose. One even suggested that "he's gonna be the one that kills Eleven."

Ahead of the teaser's debut, one fan guessed that Hopper was the American captive and that the Russians have brainwashed him. They tortured him to the point that he does not remember anything about his past.

This would explain the blank look on his face. It would also explain why the Russians did not choose him when they were looking for more food to feed their captive Demogorgon. He is still of use to them but what that purpose is won't be revealed until "Stranger Things" Season 4 comes out.

It is likely that the Russian soldiers want to get intel about his experience in The Upside Down. Viewers may remember that Hopper and Joyce went into the dark place in Season 1 in search of Will Byers. They probably want to know how they managed to come out of the toxic conditions alive. "Stranger Things" Season 4 is still filming, and perhaps fans will know more about Hopper's fate through set photos.

David Harbour in Stranger Things
David Harbour plays Chief Jim Hopper in "Stranger Things" Season 4. Netflix / YouTube