"Stranger Things" begins with the disappearance of
The boys discover that their friend, Will Byers, went missing after a routine game of Dungeons & Dragons. While biking through the woods, they stumble upon a strange girl who calls herself Eleven. The crew takes her back to Mike's house and sees that she recognizes Will in a photograph.
After recognizing Will in a photograph and demonstrating her telekinesis, Eleven convinces the boys to trust her, as they believe she can find Will. Using the Dungeons & Dragons board, Eleven indicates that Will is on the "Upside Down" side of the board and is being hunted by the "Demogorgon" (the creature).
Joyce and Chief Hopper entered the Upside Down via the Gate to search for Will. They eventually found him entangled in the web, attached to some kind of tendril extending down his throat and into his stomach; Hopper pulled it out before shooting and killing it.
Somehow, Eleven's moment of psychic contact with the Demogorgon also triggered a radical shift in the Upside Down's very nature. The realm transformed, from that point appearing as a perfect copy of the human world, frozen in the exact state as it existed on November 6, 1983.
"Stranger Things" begins with the disappearance of Will Byers. He was in the Upside Down, far out of reach of any regular human in Hawkins. But when Mike brought Eleven to his house, she saw a photo of Will and recognized him.
In Eleven's true origin story, she faces off against One after the latter threatens to destroy humanity. She is able to rip open a door to the Upside Down and sends One through, where he eventually becomes Vecna.
Millie Bobby Brown spoke about this in an interview with Variety in 2022. When the actress was asked if the Duffer Brothers explained that Eleven creates the Upside Down when she interacts with 001, she said, "They did tell me. She does. She opens the rift."
The theory predicts that Vecna wants to regain his human form, and he will use Will to do so in Season 5. Knowing that Vecna singled out Will in Season 1, it's a reasonable theory, but it might go too far. After all, Vecna already has a human form, and he has vowed to eliminate humanity.
It was in this moment that Vecna likely created the Upside Down hive mind, becoming the puppet master behind all the monsters while simultaneously growing stronger by absorbing their minds. When Eleven opened the mothergate years later, Vecna was finally able to get a foothold in our world.
Will is gay and in love with Mike, who is straight and in love with El. Unfortunately, it seems that Stranger Things is going to let Will's feelings stew in the shadows until the bitter end. (Or at the earliest, when the Stranger Things Season 4 finale comes out on July 1.)
Angela also held no remorse for her cruel actions and did not hesitate to violate boundaries, making fun of Eleven's deceased father, which led to Eleven retaliating, striking her in the face with a roller skate.
Hopper pulled the snake/eel thing off of Will and out of his throat and shot it to death, but what if that being had somehow laid eggs into Will? Then the slug-like thing he coughed up could be an infant version of the main monster that died or some other being from the Upside Down.
Now that Stranger Things season 4 has confirmed not only Will's queerness, but also his unrequited love for Mike, it's certainly interesting to look at their relationship in retrospect.
While Schnapp has refused to explicitly answer questions about Will's sexuality in the past, to him, it's always been obvious: His character is gay, and has been in love with Mike all along.
Now we know that Will's connection has always been to Vecna (not the Mind Flayer). That's why he can sense that he's still alive at the end of Stranger Things Season 4. So the connection between Will and Vec — Can I call Vecna/Henry/One just “Vec”? — is one of sheer chance.
While intending to get his revenge on Eleven and Brenner, Vecna also goes after victims who have dealt with traumatizing experiences in the past (reminiscent of his childhood and his time at the Hawkins lab).
School newspaper reporter Fred Benson (Logan Riley Bruner) fled from a deadly car accident that continues to haunt him. Patrick was targeted due to his father's abuse of him. Finally, Vecna targets Max for her trauma from witnessing Billy's death and uses Barb's (Shannon Purser) death as a way to use Nancy.
There is a lot of evidence suggesting both frightening villains were behind the vanishing of Will Byers, but we have to give the win to Vecna. There is much more evidence suggesting that it was the super-powered bad guy, and even if Vecna sent a Demogorgon to kidnap Will, it would still be Vecna who is responsible.
He gets punished with electrocution after telling Eleven that Dr. Brenner lied to her about her mother dying during childbirth. He's smart enough to use an ostensibly harmless game of chess with Eleven to inform her Dr.
One manipulated Eleven into plotting her own escape, which also involved getting her to remove the device in his neck. (Henry, however, did not tell Eleven the truth when he said Brenner wanted her dead.
In season 4, Peter Ballard notes that Kali was no longer at the lab in 1979. Given Kali's powers, it seems pretty self-explanatory as to how she was able to escape the lab. She either made herself invisible or was able to escape after manipulating the minds and visions of the guards.
So it stands to reason that Henry inherited his powers from one of his parents. And, one thing more -- remember that Victor Creel did NOT suspect Henry of being the source of the family's problems - he thought a demon was behind it.
It seems that the reason why Vecna wasn't killing for the seven years after the Hawkins Lab massacre was because he was waiting to become more powerful as the Mind Flayer and Demogorgons took more victims, as he was likely weakened after being thrown into the dimension.