Trauma fuels him 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.
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.
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.
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).
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.
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.
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.
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.
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.
Vecna's first big credited kill was Chrissy Cunningham (Grace Van Dien). He followed that murder with canonically terrible driver Fred Benson (Logan Riley Bruner) and basketball star Patrick McKinney (Myles Truitt).
What Does the Grandfather Clock in "Stranger Things" Mean? The new season shows that the four chimes of the grandfather clock symbolize the four victims Vecna needs to claim in order to enter our dimension and take over humanity.
Time is an importance aspect of his character. That's why the sound of a ticking clock can be heard when he starts to haunt his intended victims. It's why they see the clock. It's a piece of his world, his home, that leaks into his psychic connection to them.
Vecna feeds off his victims' trauma and haunts them with their own darkest thoughts.
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.
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.
He didn't name himself Vecna, the kids did. They named him after a DnD character who's a wizard, since Vecna's curse sounds like something a dark wizard would do.
As Vecna, he uses these mental abilities as a way to psychologically weaken and lure in his victims – much in a way that Pennywise, Freddie Kruger, and Pinhead do. (All of which have been cited by show creators the Duffer brothers as inspirations for the villain.) But he does have a surprising weakness: music.
The latest series of Stranger Things is another brilliant blend of horror, sci-fi fantasy and drama. But new villain Vecna is a reflection of something very real: post-traumatic stress disorder, depression and grief.
At some point in 1985, Fred was in a car accident which killed another student. He sustained facial injuries himself in this accident, which caused a scar on his left cheek.
Played by Jamie Campbell Bower, each prosthetic was glued to his skin with medical adhesive by prosthetics designer Barrie Gower and his team. For the finishing touch, Vecna was covered in "glossy slime to make him really, really glossy and wet looking," according to Gower.
Joe Manganiello's character Arkhan fought against Vecna with the adventuring party Vox Machina in the web series Critical Role. He then stole the Hand of Vecna and replaced his own hand with the artifact.
In episode 7, Vecna is revealed to be Henry Creel (played as a youngster by Raphael Luce), the son of Victor Creel (Robert Englund) and his wife Virginia (Tyner Rushing) shown in the 1950s flashbacks.
This lead to Chrissy developing an eating disorder, most likely anorexia. This meant that Chrissy was afraid of gaining weight and wanted to be thin like the other girls. She also had bulimia, meaning she would purge or regurgitate the food she ate. That's why she threw up in the bathroom.
Theory: Karen Wheeler Is Vecna's Sister From Stranger Things 4's Flashbacks.