The theory suggests that Henry Creel was less interested in punishing his “father,” Victor Creel, as he was in torturing his mother (Tyner Rushing) for the “awful thing” she had done.
Henry chose to save Eleven because he empathized with her. He saw himself in her and wanted to form a kinship with her so he could remove her from her suffering. Henry saw himself as a savior, but Eleven couldn't stomach the carnage and destruction he'd caused without batting an eye.
Brenner's twisted experiments with the children in Hawkins Lab, and in doing so, we learned that the powerful Henry Creel was the very first test subject – named 001. Brenner's ultimate motive was to create more children just like 001, with telekinetic and psychic abilities.
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.
Peter was a fake name I believe the Duffers created for him, since they couldn't really refer to him as either Vecna, 001, or Henry Creel without pretty majorly spoiling a part of Season 4.
Remember also that we have evidence that powers can be inherited -- El inherited her powers from Terri Ives, for example. So it stands to reason that Henry inherited his powers from one of his parents.
Then Eleven—who in this future moment discovers that she in fact does not have the blood of her siblings on her hands—defeats Henry Creel, sending him to the Upside Down where he gets blasted by lightening and burnt to a crisp and, thus, becomes Vecna.
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).
His first victim was Chrissy Cunningham. Vecna targeted Chrissy by using her depression and eating disorder against her in his visions. Chrissy was killed in Eddie Munson's trailer, and the first gate was opened on the ceiling.
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.
In season 4, Peter Ballard notes that Kali was no longer at the lab in 1979. Given Kali's powers, it seems pretty self-explanatory as to how she was able to escape the lab. She either made herself invisible or was able to escape after manipulating the minds and visions of the guards.
Soteria is a miniature device that, when implanted into the neck of an individual with psychokinetic abilities, inhibits that person's abilities. Henry Creel had such a device inserted into his neck by Dr. Brenner, who probably created the technology.
After One was banished into the Upside Down by Eleven, Brenner discovered through security footage that One was responsible for killing everyone in his lab, including his test subjects.
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). "I thought we lost you," he cries. "I'm still here.
He believed that the construct of time and monotony needed to be destroyed. So, in his mind, by destroying humanity, he was doing it favor. That's what makes him so evil.
However, within the red smoke of Vecna's Mind Lair, it wasn't the song itself that saved her, but the memories it conjured up. What broke through to Max was the happy, loving memories of her friends, particularly Lucas and Eleven, and these were what truly allowed her to break free of Vecna's grasp and escape.
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. This ultimately destroyed Vecna.
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 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.
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.
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.
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 reason why Vecna only has a single eye and hand is due to a betrayal by Kas", who used the sword against his former master. "In the third edition of Dungeons & Dragons, the Sword of Kas is a +6 unholy keen vorpal longsword that grants a +10 modifier to the Strength score of its wielder".
More like this. After previously having tricked Eleven into destroying the chip, Peter goes on a killing spree in the lab until a confrontation with Eleven ended in her casting him into the Upside Down - where after falling through various dimensions and sustaining various injuries, Peter was transformed into Vecna.