The Mind Flayer was thwarted two times by Will's friend, Mike, but when Will finally decided to confront the Mind Flayer, he became possessed by a piece of the Mind Flayer. The Mind Flayer slowly took over Will's body and mind, allowing to see and feel everything the Mind Flayer was doing.
With no way out, Will took shelter in the Upside Down's version of Castle Byers. As his strength grew weaker, the Demogorgon abducted Will while unconscious. His body was taken over by vines which could have been keeping him alive for the Demogorgon to feed on later, but he was soon rescued by Joyce and Hopper.
The Demogorgon
This is the monster that originally took and feasted on Barb (RIP), attacked Nancy through the tree gateway, and tormented both Will and Eleven. It's kind of like a demon that's face opens up and reveals a million, zillion teeth, accompanied by a screeching roar. It's creepy stuff!
The Demogorgon noticed her, chasing her until she returned through the portal. Will eventually succumbed to exhaustion, lying in his makeshift fort. The Demogorgon found him, breaking through the fort wall and taking him to the Upside Down library.
The Demogorgon Tried (& Failed) To Use Barb
Barb's death implied that whatever the slug does didn't take, so the Mind Flayer reached out to Will instead. It could be that the Mind Flayer needed a younger host, or Barb may have simply died while the Demogorgon was attempting to infect her.
Using past traumas to break down his victims, Vecna brought Nancy to the pool where Barb was killed by the Demogorgon and revealed her mangled corpse.
The slug Will coughed up is a baby Demogorgon. Though the actors were a little hesitant to confirm this on the after-show, it seems pretty apparent that the slug Will coughed up at the end of “Stranger Things” Season 1 was Demogorgon spawn, or at least a baby Demodog.
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.
Vecna was the one who originally kidnapped Will in season 1.
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.
The Duffer Brothers had Vecna planned from the start, which is how they were able to tie his character into earlier seasons. Stranger Things revealed Vecna was also behind the Mind Flayer that appeared in season 2.
What did Vecna want with Will? The theory predicts that Vecna wants to regain his human form, and he will use Will to do so in Season 5.
The theory is that the Demogorgon is actually a warped version of Will Byers who has been corrupted by the Mind Flayer in order to assist in its plans to take over the world.
Eleven has a memory during this episode and realizes that 001/Henry Creel (Jamie Campbell Bower) wants her to join him on his evil journey, and she banished him to the Upside Down. 001 then transformed into Vecna, the horrifying Stranger Things villain.
Via this psychic contact, a tear within the fabric of space-time was created; a non-temporary gate to the Upside Down. Through the Gate, the Demogorgon traveled into Hawkins. There, it abducted Will Byers and killed Barbara Holland.
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.
Following Eleven's resistance, Vecna sought after Eleven's 'power', which he identified as "a means to open [his] own doors" (gates).
Demogorgon is first mentioned in the commentary on Statius's Thebaid often attributed in manuscripts to a Lactantius Placidus, (c. 350–400 AD). The Lactantius Placidus commentary became the most common medieval commentary on the poem by Statius and is transmitted in most early editions up to 1600.
You will naturally freak out if a slimy pest gets on you. Slugs are carriers of diseases and parasites, yet they are not aggressive towards humans. So, even if you are uncomfortable or scared, it is advisable to remain calm throughout this situation.
At his empire's height, Vecna was betrayed and destroyed by his most trusted lieutenant, a vampire called Kas the Bloody-Handed, using a magical sword that Vecna himself had crafted for him, now known as the Sword of Kas.
Vecna kills Chrissy, Fred, and Patric, three characters we were just beginning to know. The villain also almost takes our beloved Max, but she is saved by the power of music! Finally, episode 7, titled “Chapter Seven: The Massacre at Hawkins Lab,” left audiences with a pretty big cliffhanger: Vecna enters Nancy's mind.
How Many People Has Vecna Killed? Eleven's count may be high, but Vecna (Jamie Campbell Bower) has her beat. The monster formerly known as Henry Creel has directly killed 40 people.