This article contains spoilers for Stranger Things season 4.

Stranger Things season 4’s main villain, Vecna, is ultimately revealed to be Henry Creel – Dr. Brenner’s “Number One” at the Hawkins Lab. The story of Stranger Things is, surprisingly, rooted in the real world – specifically in the CIA’s Project MKUltra, a secret mind control program that was launched in 1953. The experiments being conducted by Dr. Brenner at Hawkins are supposed to be an offshoot of Project MKUltra, one that has unwittingly threatened the entire world.

Dr. Brenner’s experiments have always been mysterious. It’s long been unclear how he realized certain procedures could be used to ensure children were born with the potential to develop unusual powers, including telekinesis, telepathy, and illusion casting. The sheer scale of Eleven’s success was demonstrated in Stranger Things season 4, which revealed he had created no less than 14 superhuman children. Curiously, though, the identity of his first test subject – his “Number One” – was a secret kept even from the other children.

Stranger Things season 4 finally unraveled the mystery, with episode 7 revealing the true identity of Number One. In a shocking twist, it turned out Number One is in fact the new villain from the Upside Down, Vecna. Stranger Things has always been quite open about drawing inspiration from superhero comics, and season 4 exploits a classic trope in which Eleven must face a twisted mirror image version of herself.

Henry Creel/Number 1’s Powers Explained

Dr. Brenner’s children were granted powers by treating their mothers with psychedelic drugs during pregnancy. Henry Creel appears to be different, however; there’s no evidence his mother ever experimented with LSD. Rather, his powers seem to be natural, developing around puberty. There’s an interesting parallel between Henry Creel and mutants in Marvel’s X-Men comics, where an X-gene activates at puberty. Whatever the origins of Henry Creel’s powers may be, he certainly shares the common character flaws of psychics in those comics as well – because telepaths tend to have something of a god complex.

Henry Creel shares all of Eleven’s powers, and then some. He is a telepath, able to enter the minds of others and probe their deepest fears and darkest memories; Creel also possesses Kali’s ability to project illusions into the minds of others. His telekinesis operates on a scale matched only by Eleven, making her the only one who can match him. Creel discovered his powers when he was just a child, and he delighted in tampering with the minds of others.

How Henry Creel Became Dr. Brenner’s First Test Subject

Henry’s mother sensed something was wrong with her son, and she reached to a scientist called Dr. Martin Brenner. Henry was furious when he learned this, and he lashed out, killing his mother and sister in the Creel house – but overexerting himself, collapsing into a coma when he attempted to murder his father as well. When he awoke, Henry found he was now in the care of Dr. Brenner, who must have already begun experiments that led him to realize the boy’s potential. Brenner initially sought to control Henry, even figuring out how to inhibit his powers somehow, but he soon found Creel was unstable and unreliable.

Unable to control Henry Creel, Dr. Brenner instead turned to trying to recreate him. Presumably, ECG scans had allowed Brenner to identify what parts of Creel’s brain were active when he used his powers, and he recognized similar patterns in children whose development in the womb was influenced by psychedelics. He must have tried out different combinations on various pregnant women, unable to perfectly duplicate Number One’s powers – but coming closest with Eleven.

Number 1’s History At Hawkins Lab: Why Was He An Orderly?

Number One became an orderly, helping Brenner raise the kids at Hawkins Lab. It’s unclear why Dr. Brenner decided this was safe, but it’s likely he was manipulated by Creel, a smooth talker who knew just how to twist people’s better natures against them even without his powers. Perhaps Brenner believed Creel would have a natural bond with those he considered his own “kind,” and thought this could be a way to redeem him. Whatever Brenner’s hopes may have been, they were dashed, for in truth Creel was simply playing for time. He cultivated a close friendship with Eleven, recognizing her naivete and the powers that made her so much greater than the others. He fooled Eleven into freeing him from Dr. Brenner’s control, and then rampaged through the lab.

How Number 1 Turned Into Vecna

However, Number One failed to realize how powerful Eleven was. Realizing she had been tricked, she confronted Henry Creel and engaged him in a telekinetic duel. She managed to overwhelm him, and her powers somehow opened a window through the dimensions – allowing her to blast him out of this universe. The experience was a traumatic one, leaving Number One’s body horrifically scarred. He emerged in the Upside Down, and lived there for years, making his home in a twisted version of the house he had grown up in as a kid. All life in the Upside Down is bound together by the Mind-Flayer’s hive mind, and at some point, Creel became part of it – transforming into the being who has been named “Vecna.” The kids assume Vecna has become the Mind-Flayer‘s “five-star general,” but in truth Stranger Things season 4 volume 1 raises the disturbing possibility he has actually taken control of the entire hive mind.

Vecna’s Curse & Plan Explained

Vecna shares all Eleven’s powers, which means – like Eleven – he has the ability to open Gates between the Upside Down and Hawkins. There appear to be two requirements for Vecna to open a Gate; a strong mental contact and a power source. The hive mind itself serves as the power source, allowing Vecna to scan Hawkins looking for people with buried grief and repressed shame. When Vecna has chosen his target, he establishes an initial contact to begin tormenting them, forcing them to confront their worst nightmares – and then ultimately killing them with his telekinesis. A Gate is opened at the moment of death.

Vecna’s endgame remains something of a mystery, but it’s possible the mysterious earthquakes shaking the Upside Down are a clue. These raise the possibility Vecna’s Gates are causing some sort of dimensional instability, bringing the Upside Down ever closer to Hawkins – and potentially leading to a collision of the pocket dimension with the real world. If this is indeed the case, Stranger Things season 4 could end with a state of open war between Hawkins and the Upside Down.