The history of the Upside Down remains mysterious. Exactly how and why it came into existence is unclear. Dustin theorised the Upside Down had existed for thousands, if not millions of years.
Did Eleven create the Upside Down? The first known human contact with the Upside Down was in 1979 during Eleven's fight with Vecna. During the match, Eleven was able to overpower Vecna, using her psychic abilities to keep him pinned to the Rainbow Room wall as his body disintegrated.
The Upside Down is stuck in 1983.
In a Deadline interview, Ross Duffer says that “that's something we don't answer in volume two, and that is really the key plot point, the key question that is going to drive our final season as we try to wrap up this story and give the rest of the answers out.”
All this means Eleven did not create the Upside Down. This Hellish dimension already existed, ruled over by the hive mind of the Mind-Flayer. She did, however, transform it - drawing the different planes of existence closer together, and placing a copy of Hawkins upon the Upside Down like some kind of overlay.
The second discovery was that the Upside Down – previously thought to be a copy of the normal world where time ran in parallel – was stuck in the past. Specifically, time there had stopped moving forwards on November 6th 1983, the exact date that Will Byers went missing after Eleven opened a gate to the Upside Down.
With Vecna taking centre-stage in the fourth season of Stranger Things, eagle-eyed fans have been spotting clues that he's actually been around since season one.
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.
In a fit of rage, Henry used his restored powers to brutally murder the other test subjects and workers, and attempted to do the same to Eleven. However, Eleven stood her ground and ultimately overpowered him, sending him through a gate to the Upside Down; there, he gradually transformed into the being known as Vecna.
Much to One's surprise, Eleven ends up being more powerful than even he is and she sends him to the Upside Down, creating a portal in the process and also turning One into Vecna.
We still don't know why Vecna waited seven years after being banished to the Upside Down before starting his murderous rampage.
Brenner's words make it seem like Vecna subjugated the entire Upside Down and, thereby, created the realm's hive mind. In other words, the Upside Down's hive mind is actually Vecna's mind because everything that he dominates becomes a part of him.
As part of a featurette spotlighting Stranger Things' production, the designer explained that the Upside Down is "frozen" in 1983, several years after Eleven exiled One/Vecna to its clutches. As a result, the Upside Down is entirely styled with elements from season 1, following Eleven's escape from Hawkins Lab.
September 8, 1979: Henry plots the Massacre at Hawkins National Lab, and Eleven sends him into the Upside Down.
Founded by Australian fashion icon Jodhi Meares, THE UPSIDE's early ethos laid in establishing a bold brand that catered to sartorially sophisticated and time savvy individuals who led demanding lives but cherished their training.
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.
As Vecna continued to go after young victims in order to open more portals, he set his sights on Max Mayfield, since she was investigating the deaths of Chrissy and another student named Fred Benson with help from her friends (including Dustin, Steve, and her boyfriend Lucas).
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.
Vecna's Hand
This is a reference to the D&D character Vecna, for whom this Vecna is named; the D&D Vecna has a monstrous hand infused with dark magic. The design of Vecna's hand is also a nod to Freddy Krueger, the Nightmare on Elm Street villain who had a huge influence on this season in general.
Then there were the three poor teens of Season 4. 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).
Character biography
Vecna was born as a human, centuries ago as a member of the untouchable caste in the Flan city of Fleeth on Oerth. He was initially trained by his mother, Mazzel, in the art of magic, before she was executed by the government of Fleeth for practicing witchcraft.
The Upside Down Is Another Earth, Not Just Hawkins
Redditor acebarrett54's theory is, "The Upside Down is a fully alternate Earth. A lot of people think that the Upside Down is just an alternate version of Hawkins, but it actually encompasses the entire world."
The Upside Down is generally accepted and referred to as an alternate dimension of the human world, given that it's pretty much a mirror of it but in a state of decay – but there might be a completely different reason as to why this “dimension” looks exactly like this one, and it's because it's the same, but in a ...
Another idea is that, if the Upside Down has indeed been in existence for eons, One entered a barren landscape, only for the realm to adjust once Upside Down lifeforms had gained intelligence from Hawkins. This would also explain why the Upside Down is based on Hawkins only.