Season 3 of Netflix's sci-fi drama Stranger Things left fans with many unanswered questions. Where are the Byers and Eleven moving? How will the kids maintain their friendships? What horrors does the Upside Down still hold? Did Hopper really die when the gate was closed? (Thankfully, this last question has already been answered.)

Another looming question from Season 3 has to do with Eleven's powers, which grew weaker and weaker until she was unable to use them after she was attacked by the Mind Flayer. No hints have been released as to how El will regain her telekinetic abilities, but according to a theory posted by Screen Rant, she may need the help of a familiar face.

The sinister Dr. Brenner was a key antagonist in the first season. He wasn't just the reason the gate to the Upside Down opened in the first place—he was the one who encouraged Eleven to make contact with the Demogorgon—he also covered up Will's disappearance and led a manhunt for Eleven after her escape from Hawkins Lab. As a senior research scientist and the director of Hawkins Lab, Dr. Brenner took Eleven from her mother when she was just a baby, spearheaded Eleven's telekinetic training, and forced her to call him "Papa."

All in all, Dr. Brenner is a pretty shady character, and despite being attacked by the Demogorgon in the Season 1 finale, producer Shawn Levy confirmed he is still alive.

Screen Rant poses a fan theory from Reddit user jimbo805, who posits that Eleven will turn to Dr. Brenner for help in reviving her powers in her desperation to protect her loved ones. The fan believes Season 4 will end like this: "Eleven finally tracks down Brenner. She tells him what she wants him to do. Then we see Brenner with the most evil grin ever seen on a mad scientist as he begins his evil machinations." Another cliffhanger? We'd believe it.

The return of the mysterious doctor could answer the unresolved origin of the Upside Down, and it would be awesome to see El confront the man who experimented on her nearly her entire life. Here's to hoping we get Season 4 of Stranger Things sooner than later, considering filming is currently on hold due to safety concerns surrounding COVID-19.