The theory that Vecna is actually Billy Hargrove may come with an interesting twist, which suggests that Vecna isn't Billy per se, but rather a monster imitating Billy in order to torment Max and Stranger Things season 4's characters.
Billy Hargrove may have had a short run on Stranger Things, but it was definitely memorable. With his mullet and mustache, he made the perfect vessel for Season 3's villain. But during Season 4 and the rise of Vecna, his role was limited to his grave being the setting of Vecna's first encounter with Max.
After Stranger Things season 4, it is clear that Vecna sent the Mind Flayer after Eleven to steal her powers from her. Considering the importance of Max's and Billy's relationship to the overall storyline in the latest season, it's interesting to note that Billy was the Mind Flayer's first victim in season 3.
The final scene of Volume 1 shows a shot of Vecna, and a close up of the 001 tattoo on his arm, confirming that Henry Creel, a.k.a. Number One, became Vecna.
Presumably, Vecna chose to conceal his true identity as he spoke through Billy, explaining some of the strange pronouns used during the conversation.
Seeing Stranger Things' Vecna Made Millie Bobby Brown Cry
She's a 10, but she cries when she sees Vecna? She's an Eleven.
Vecna is the Mind Flayer. The Mind Flayer is Vecna. Vecna (Jamie Campbell Bower) has a connection to the very beginning of 'Stranger Things.
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.
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).
"Vecna seems to be actually intrigued by Nancy being able to figure him out, to be able to get this close to the truth... I think this is more Vecna's narcissistic traits that pull him to Nancy, why he wants to give her this information."
His sister Max, upon seeing this, takes courage and uses a syringe with tranquilizer injected into the neck leaving it insensitive, finally at some point it returns to the house without knowing if it still has remorse.
Ultimately, it is revealed in Stranger Things season 4's finale that the reason why Vecna was killing Hawkins teenagers was to create a massive gate that merges the Right Side Up with the Upside Down - and he specifically needed four bodies to do so.
Deciding to make a change, Billy physically held back the Flayer, who killed him by stabbing him in the chest. In his final words, he apologized to Max.
Next up, the viewers go on to theorise that One/Vecna is actually Eleven's dad. Yep, told you it was wild. The theory claims that Brenner wanted to create a child with stronger powers, so he waited until One was old enough to become a father.
On March 24, 1986, Max Mayfield wrote a letter in Mike's basement, that she was going to read to her step-brother Billy Hargrove, following his death and her being cursed by Vecna. She completed the letter having reflected on her life after being cursed, wanting to say some final words to Billy.
In what is really his only redeeming moment of the series, Billy stands in front of Eleven and allows the Mind Flayer to kill him instead, being violently stabbed through the chest and subsequently dying in a horrified Max's arms.
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.
Vecna's obsession with time appears to be linked to his hatred of humanity. He views time as a human imposition on the natural world; an attempt to impose order on nature.
Once he takes control of the mind, he traumatizes them by showing the visions of their dark past. He takes them to unknown places and gives them a glimpse of himself. The pain of his victims doesn't end here. Every single one of his victims experiences nose bleeding and severe headaches as well.
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.
Realizing he had tremendous psychic power, he haunted his family with visions before ultimately killing most of them. His father was framed for the murders and locked away in a mental hospital as a disturbed serial killer. Henry then found himself in the care of Brenner, who decided he wanted more kids like the boy.
Vecna was the original child studied by Dr. Brenner and the son of Victor Creel. He's the infamous Number One, but had his powers blocked and worked as an aide in the Hawkins National Lab.
The episode then cuts to Vecna in 1980s Upside Down, zooming in on his arm, where a tentacle slides away to uncover 001 tattooed on his wrist. So Vecna is 001, who is also Victor Creel's son.
Then, as he was falling through the Upside Down, One became the creature Vecna after lightning struck him in such a way that it changed his skin and made him into the monster he is now.
After inflicting protracted suffering, Vecna finally executes the victim, using his powers to make them levitate before snapping their limbs and gouging out their eyes.