Vecna lives in the Upside Down and preys on people's past traumas and guilt. The monster curses its victims, making them relive their trauma in progressively more gruesome ways until it violently kills them.
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's use of his victims' guilty conscious to terrorize his prey is an obvious tool in his arsenal. What is more subtle and powerful is that he uses shame to isolate and control. All of his victims, starting with Henry's father, believe that if people know the truth about them, they will face rejection.
Using his supernatural psychokinetic abilities, Vecna can probe and influence the minds of others. Motivated by a cruel and misanthropic philosophy, Vecna targets particularly traumatized, mentally ill or insecure individuals.
While the season 4 marks Vecna's first murder streak in Hawkins, it turns out the monster first emerged in the '50s. Super-sleuth Nancy finds out that the monster previously targeted the Creel family, led by patriarch Victor Creel.
Vecna as a Means for Externalizing Trauma and Depression
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.
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.
Vecna feeds off his victims' trauma and haunts them with their own darkest thoughts.
Vecna lives in the Upside Down and preys on people's past traumas and guilt. The monster curses its victims, making them relive their trauma in progressively more gruesome ways until it violently kills them.
Netflix Vecna has plans for world domination. Essentially, Vecna hates humanity, and wants to take over their world. He had hoped that Eleven would help him achieve this goal. But when he realised she wouldn't, Vecna instead used her.
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.
And while his usual modus operandi is to embody his victims' negative self-talk (another very real psychological phenomenon), this time he is telling Nancy his plans and then releasing her so she can report back to everybody—Eleven included—that the end is nigh, with the goal of discouraging and disempowering them.
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.
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.
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.
Dr. Brenner (Matthew Modine) clarifies that Vecna "consumes" his victims, as he isn't interested in simply killing them - meaning Vecna takes everything about and from a person.
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'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.
She breaks free, momentarily incapacitates Vecna, and runs with the determination to live toward her friends, dodging debris that Vecna throws in her path. Max hurls herself through the portal, awakes from the trance, and is held by Lucas (Caleb McLaughlin).
Together, their powers combined are the exact powers of 001/Henry. Fans are now theorising that the powers of both 011 and 008, who have the combined power of 001, is what is needed to finally match and defeat Vecna. To put it simply, 011 + 008 + [with the combined power of] 001 = 020, a.k.a. Erica's critical hit.
In the D&D realm, a defining feature of Vecna is that he's missing his left hand and left eye. 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.
His method of killing is ritualized. Vecna started twisting bodies and removing eyes before imprisonment in the UD to fuel its own individual power. It takes the eyes to help hold the souls in darkness and because it did not wish to be observed.
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.
He was eventually destroyed, and his left hand and left eye were the only parts of his body to survive. Even after the character achieved godhood—being a member of the third edition's default pantheon of D&D gods (the pantheon of Oerth)—he is still described as missing both his left eye and left hand.
His first three victims — Chrissy Cunningham, Patrick McKinney, and Fred Benson — are all peers of The Party, people they know from school, which makes Vecna's terror all the more real.