Turns out, he needs exactly four dead kids, like the four chimes of his signature clock, as they are his necessary sacrifices in order to open enough small gates in Hawkins, so that he can create that earth-shattering gate in the final episode.
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.
The new season shows that the four chimes of the grandfather clock symbolize the four victims Vecna needs to claim in order to enter the Right Side Up and take over humanity.
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).
Brenner (Matthew Modine) states in the Stranger Things episode "Papa" that Vecna "consumes" everything about his victims, Vecna targets traumatized victims because it builds for him a well of sad and angry memories to draw from. With each victim, he can become gradually more powerful.
Chaiken suggests that while Vecna is a source of horror in Stranger Things, the monster can also serve as a useful vessel for externalizing issues like trauma and depression.
Vecna draws power from sad and angry memories and that is the main reason he targets traumatized teens. Those teens are a well of power just there to be absorbed. This is not just a theory, Vecna himself told Eleven about the power that angry and sad memories hold.
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.
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.
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.
She Doesn't Have a Great Aim
After the Hawkins team develops a plan to defeat Vecna, Nancy is in charge to blow his head up with a shotgun. However, either she didn't have a great aim or she was trying to play it safe because she didn't hit him in the face even once, and that may be the reason why Vecna is still alive.
While his usual strategy is to mimic his victims' self-deprecating thoughts (again, a very real psychological phenomenon), this time he is telling Nancy his plans and then releasing her so she can inform everyone—including Eleven—that the end is near, with the intention of demoralising and disempowering them.
Stranger Things' season 4 introduced the vicious Vecna, who kills people by infiltrating their minds and killing them from the inside. He can be stopped, however, if his victim listens to their favorite song.
What was Chrissy's Trauma? Chrissy's life appears to be free from flaws on the surface, but in reality, she is struggling terribly to conceal her depression and self-image stemming. She was struggling with these issues, which resulted in her developing an eating disorder due to her mother's verbally abusive comments.
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.
When One massacres the rest of the children in Hawkins Lab, Eleven banishes him to the Upside Down in the same way she banishes the Demogorgon from season one. One is sent hurtling through the Mind Flayer's lightning and is horribly disfigured, transforming into Vecna.
Seeing Stranger Things' Vecna Made Millie Bobby Brown Cry
She's a 10, but she cries when she sees Vecna? She's an Eleven.
We know Eleven was born in 1971, which means her mom got pregnant with her during the tests, sometime in 1970. A 1959 flashback in the mid-season 4 finale reveals a 12-year-old One (Jamie Campbell Bower). That puts One, a.k.a. Vecna, as 24 when Eleven was born.
If Vecna can overwhelm their victim with fear, and keep them from resisting, their fate is almost certainly sealed. In the real world, he makes the victim levitate while in their trance, before snapping their bones and neck, and crushing their eyes.
This is because his trusted accomplice, Kas the Bloody-Handed, betrayed him and used the sword Vecna created himself to chop off his left hand and remove his left eye. This ultimately destroyed Vecna. Though they're clouded with cataracts, Vecna in Stranger Things has both of his eyes.
And he saw the possibility for escape when he realized the extent of Eleven's untapped potential. 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.
During Henry's time as an orderly at Hawkins Lab, he took a particular liking to one of Brenner's test subjects, Eleven. After witnessing her being bullied by the other test subjects, he believed both of them were similarly misunderstood, and also believed Eleven to be the most powerful of the test subjects.
After taunting her with incessant chiming from a grandfather clock and appearing before her in hallucinations, Vecna eventually kills her in an incredibly gruesome way. First, she went into a trance with her eyes rolling into her head, then she began to levitate before her eyes were removed and bones were snapped.
After learning how Victor Creel was able to evade death back in 1959, Robin and Nancy deduce that playing the victim's favorite song can help them escape the trance that Vecna places them in, with music and happy memories being the only way to keep Vecna's fatal curse at bay.
Unlike the reporters at the Hawkins Post, Fred treated Nancy with respect. Though Fred appeared to be bright and level-headed, he harbored extreme guilt for his role in the fatal 1985 car accident, and believed many people look at him as a "murderer." This guilt and mental unrest made him a target of Vecna.