Spoiler Alert

Stranger Things‘ Upside Down has always existed without explanation. Not until season four did any character even consider how old it is, let alone how or why it’s there at all. That hasn’t been a problem, though. The mere presence of an evil parallel dimension, a place full of monsters that stands as a dark mirror to the real world, was enough for the horror series to tell a compelling story. But Stranger Thing 4’s seventh episode changed everything we know about that sinister realm. The truth about Vecna’s origins provided new insight into what the Upside Down really is. And that revelation gave the show an emotional depth that transformed both the terror and beauty of what the series is really about.

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Eleven did not merely defeat One, she sent him to the Upside Down. Her attack was powerful enough to open a doorway between worlds that had not existed. And once that evil dimension had Henry Creel in its grasp, it turned him into the twisted Vecna. But as sordid and entertaining as One’s own tale is, the specifics of his life, how Eleven banished him to another plane, and what happened to him there tell a far more important story. These revelations finally reveal what the Upside Down really is and where it came from: us.

The mysterious Hawkins Lab orderly told Eleven she could unleash her powers the way One did. She needed to find strength in a memory by remembering something that made her “sad, but also angry.” That’s exactly what she did when she found herself at One’s mercy. Eleven thought of her screaming mother being pulled away from her. The rage, hurt, and agony of that moment, of being denied her mother’s love, was so intense it connected Eleven to the Upside Down. It took the very worst moment of her life to open a pathway to our world’s dark parallel.

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What happened to One inside that monstrous dimension also shows what the Upside Down truly is. Unlike Barb, Billy, or any other person who found themselves consumed by that plane; One did not become its victim. It did not attack him. Henry Creel—an evil man who loved no one, someone with the darkest of souls and a heart full of hatred—became the Upside Down’s soldier. The Upside Down is a hive mind, and Henry had the same warped mind.

And yet, his transformation did not entirely cut him off from the real world. As Vecna he can find his way back there using the same emotional connection Eleven did to send him to the Upside Down. Vecna enters his targets’ minds via their own terrible pasts. People like Chrissy, Fred, Nancy, and Max, those who burdened by tremendous personal pain, are vulnerable to Vecna’s curse because his curse is pain.

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From Eleven’s opening of that portal, to Henry Creel’s transformation, to Vecna’s killing spree, the Upside Down can only be accessed by the most painful emotions. Everything about that realm is defined by human suffering. And therein lies the answer not only to Dustin’s question about its age, but the question of what it is. The Upside Down is defined by pain because that’s what created it. That dark realm that physically mirrors the real world, but without any of its light or love, is the physical manifestation of human suffering. It’s been around as long as people have felt anger, guilt, remorse, sadness, rage, and every other painful emotion. It’s home to all of the things that pull at our soul and keep us in darkness. That’s why it became Henry Creel’s domain. He is evil, and as his father Victor said, “All evil must have a home.”

Knowing humanity created the Upside Down, even unintentionally, is far more terrifying than that place merely existing on its own or being the creation of some supernatural entity. The Upside Down was always there and will always be there so long as we must watch our loved ones die and suffer. The monsters who dwell, the ones that want to rob us of our lives, they’re our monsters, the ones we create every time we hurt someone and create more heartache in the world. That sinister world mirrors ours because it’s a reflection of the darkness we all feel in our bleakest moments and greatest failings. The Upside Down is not an inhuman world as we’ve always thought. It’s a world made by humanity at its worse.

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That’s a bleak development even for a horror show like Stranger Things. Living with sadness and anger is hard enough without thinking those feeling have manifested into physical entities. And yet this development also comes with great hope. There cannot be light without darkness, nor pain without joy. We would not feel guilt like Max, or experience grief like Nancy, if we did not also feel love. And that’s why this revelation about the Upside Down has also added a new emotional resonance to the series, which Stranger Things 4 itself explored even before we saw Eleven vanquish One and learned what that terrible place really is.

After Eleven went off with Dr. Owens, Will and Mike talked about what to do next. Mike thought they had to trust the government, but Will wasn’t so sure. Will reminded Mike who really saved him from the clutches of the Upside Down. It wasn’t Dr. Owens or any soldiers. “He wasn’t able to protect me,” said Will. “That was you guys who saved me. That was you guys.” And when Mike responded it would be up to them yet again to save Eleven and Hawkins, Will answered, “It always is, isn’t it?”

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He’s right. It’s never been men with guns, scientists, or doctors who rescue them. It’s always been that group fighting to protect each other through sheer will and determination borne of their love for one another. Stranger Things has always been a show about friendship, but now that we know exactly what they’ve been battling—literal human despair—this story is so much deeper and meaningful. And in the very same episode Will expressed that idea so beautifully, it’s final moment, one of the most moving scenes in the show’s history, made clear why that faith in one another is as hopeful as the Upside Down is dark.

Max spent the first half of Stranger Things 4 apart from her friends. She shut herself off from them emotionally, because she unfairly blamed herself for her brother Billy’s death. Rather than turn to her loved ones for support, she lost herself in a world of despair. She got lost in her grief and pain. Vecna didn’t pull Max into the Upside Down, she was already living there. Just as Chrissy and Fred had been. It’s why the monster said to her, “There’s a reason you hide from them—you belong here, with me.”

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Only a creature like Henry Creel, a being without humanity, belongs in the Upside Down. He doesn’t know what it means to be loved or to love someone. That’s why he told Max her friends couldn’t help her. Vecna doesn’t understand the power of those connections. Henry never knew what is was like to have someone who can pull us out of despair when we can’t see out of a hole we keep digging. He has no one who can light a way back when we’re lost in grief. Henry never had family or friends who would risk it all to save us. That’s why it wasn’t Kate Bush’s song that saved Max. It was the good memories that song reminded her of.

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While Eleven’s past pain opened up a door to the Upside Down, the love Max once felt opened up a door to the real world. Vecna was right about one thing. Max had been hiding from her friends. But when she found strength in the best of her memories, moments of unquestioned happiness with her friends, she literally ran back to them. They saved her from being lost forever in a world of pain.

We now know what the Upside Down is and why it exists. We finally know why it looks just like our own world and how we can end up there. And it’s more horrifying than we ever could have imagined. But that’s exactly why Stranger Things is more beautiful than it’s ever been. Those friends have always stuck together other, but knowing what they’re saving each other from makes their fight more meaningful.

We’re always fighting our own darkness. Our pain will always try to consume us and keep us from those we love. But we can defeat it together. And when we do, just like Max said when she returned to her friends and their love, we can tell them, “I’m still here.”

Mikey Walsh is a staff writer at Nerdist. You can follow him on Twitter at  @burgermike. And also anywhere someone is ranking the Targaryen kings.