Stranger Things season 4 can solve the long-running mystery surrounding the identity of Eleven's birth father. Born and raised in Hawkins Laboratory, Eleven never experienced an ordinary childhood. When she escaped at the onset of the Netflix series, she was given a chance to investigate her own origins and the potential of her special abilities. While doing so, she eventually became the adopted daughter of Chief Jim Hopper. Now that the two are separated for the time being, Stranger Things can finally shed light on Eleven's real dad.
In previous seasons, Stranger Things revealed Terry Ives as Eleven's biological mother. While in college, Terry volunteered to participate in Project MKUltra, a series of experimentations overseen by Dr. Martin Brenner at Hawkins Lab. She became pregnant while being subjected to mind-altering drugs, and Brenner kidnapped the child, who was born as "Jane Ives." When Terry attempted to retrieve her daughter, the woman was forced into having electroshock therapy, leaving her in a catatonic state. Jane, who was renamed "11," or Eleven, was then raised in the lab as a test subject due to her telekinetic powers. While in the lab, she referred to Dr. Brenner as "Papa" since he acted as a father-figure until her escape.
With Terry unable to care for Eleven due to her catatonic state, Hopper became the one to step up as the young figure's primary guardian. As Eleven entered deeper into her teenage years in Stranger Things season 3, her relationship with her adoptive father was complicated but loving. Though the show never made an effort to provide answers when it came to her biological dad's identity, it didn't necessarily need to with Hopper's presence. With Hopper presumed dead in Eleven's mind because of the events of the Battle of Starcourt, the teenager could be motivated go on a journey to investigate her origins.
How Hopper's Absence Can Provide Answers Into Eleven's Origins
Not only was Eleven betrayed by Dr. Brenner, but she felt another sense of immense loss due to Hopper's "death." Season 4 can use Eleven's grief to propel her into searching for answers regarding her true existence. Hopper will ultimately reunite with his adopted daughter, seeing as he's actually alive, but until then, the long-term mystery into Eleven's past can be put into the spotlight. Some viewers have theorized that Dr. Brenner is Eleven's biological dad, or perhaps he forced an artificial pregnancy while Terry served as a test subject.
Interestingly, a Stranger Things 2019 tie-in novel titled Suspicious Minds introduced Eleven's biological dad. Before Terry took part in Project MKUltra, she was dating a young man named Andrew Rich. At some point, Terry supposedly became pregnant with Andrew's child. Before he could meet his infant daughter, Andrew was drafted to serve in the Vietnam War, which may have been orchestrated by Dr. Brenner. He was killed while serving, meaning that he never had the opportunity to meet his child, nor did he learn the truth about the experiments used on Terry.
While there's an expanded universe with tie-in titles, it's unclear if Suspicious Minds is considered canon based on plot holes the story has created. For now, the mystery surrounding Eleven's birth father is alive and well in the TV series. Maybe Dr. Brenner will return in Stranger Things season 4 to finally provide more answers. There's also a chance that Andrew will be introduced through a series of flashbacks to match the prequel tie-in novel. Only time will tell when Netflix presents the next chapter of the beloved sci-fi series.