Right from the get-go, Stranger Things introduced audiences to a very unique location in the form of the Upside Down. This dark place has been the reason why Hawkins, Indiana, has been visited by many monsters in recent years. But if one unexplainable realm wasn't enough, then Stranger Things Season 5 has got you covered.
Enter Camazotz, a reality unlike anything we've seen so far in the series. What makes it an interesting location is the fact that people like Max, Holly, or Derek can be physically in different places, yet they can all meet within Camazotz. So, how is that possible? How can beloved Stranger Things characters be at two very different places at once? Well, as is the case with many unexplainable phenomena in science fiction, it all comes down to dreams... sort of.
Camazotz is the physical representation of Vecna's mind
If you could take all of your memories and transform them into a physical maze, then the result would be Camazotz. Every location you'd ever visited and every person you'd ever met would be there. From your earliest memories to the dish you ate yesterday. Entering Camazotz quite literally means entering a person's mind. Unfortunately for our heroes, this realm is created by none other than Vecna himself, which means it is filled with the monster's memories.
Stranger Things has always played with the idea of a character being physically in one place, while their mind is in a completely different realm. Let's go back to the opening episode of Season 4 for a moment. Remember how Vecna hunted Chrissy? Well, for a moment there, Eddie could see Chrissy's body in his own home, completely unconscious and still before it started levitating. Meanwhile, Chrissy was running for her life, trying to escape Vecna in the villain's mind. She was in two different places at once, and now the same goes for Holly and Max.
A big question then becomes, how can people like Chrissy see locations from their own past if everything takes place inside Vecna's mind? How could Vecna know what Chrissy's parents looked like, for example? A similar scenario happened with Max when she tried to escape Camazotz for the very first time. When Max followed the trail of all the memories where she made an appearance, we see her replay moments where Vecna wasn't present (such as her near-death in the real-world version of the Creel house). So, how can Vecna's mind contain memories in which he didn't take part?
It's important to remember that whenever Vecna hunts for a new victim, he invades their minds. He can see everything they went through, every place they had ever been, and every person they ever interacted with. All this knowledge goes directly to Vecna's mind, meaning the villain can then recreate it in his own personal realm. That's why people like Chrissy or Max can see certain scenes in Camazotz where Vecna wasn't originally present.
One of the many downsides of being trapped in Camazotz is that your real body falls unconscious in the real world. Max has been in a "coma" this whole time because her mind has been trapped in Vecna's personal hellscape. The same goes for Holly, who is unconscious in The Abyss (as coined by Dustin), yet her mind is in Camazotz for a very long time. We also can't forget about the rest of the 12 missing kids, who are in the exact same position.
The name Camazotz comes from the novel A Wrinkle in Time, which Holly loves to read. That's why it was she who named this twisted reality in the first place (and has been reminding Max what to call it for a long time). Stranger Things introduced Camazotz as a brand new world where people can't be physically hurt, but they can be haunted by their very own ghosts. The Duffer Brothers have called this storyline their "new Russia storyline", as it contains very few characters and eventually integrates with the rest of the other arcs.