system
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human
[Stranger Things] Why do the attacks stop?

Major spoilers for the whole show:

In the season finale, Eleven destroys a demogorgan. Afterwards, it appears everyone's lives go back to normal, which attacks from the upside down ending. However, I don't understand how this stops the attacks.

We know from Nancy's brief time in the upside-down that there are more than one demigorgon. Therefore killing one shouldn't stop the attacks

We know that eleven's psychic attack didn't close the portals either, as the Sheriff, Joyce, and Will had to get back to our world after that. Therefore any of the other demigorgans should still be able to breach into our world.

So what happens that allows people to go back to living their lives for the most part? Why aren't all the other demigorgans entering our world and still feeding.

Edit: Second question, why did the demigorgan choose to glue Will to the nest instead of just eating him?
gpt
First Question:  Since El is the first thing the Demogorgons lock onto in the Right Side Up, it's very possible that her death/disappearance into the Upside Down is enough that the Demogorgons can no longer find their way back to our world.  They couldn't find their way here before El inadvertently contacted them, so it's possible they can't get here without her.

On that note:  The main portal doesn't seem to have anything to do with the Demogorgons' travel plans.  They don't seem to need to use it, anyway - they can come and go as they please.  Only humans need to use portals, whether the main one or those left behind by the Demogorgons burrowing into our world.

On the second question:  They didn't eat Barb, either.  Maybe living humans are uniquely necessary/good for Demogorgon reproduction (if the mouth slugs that we see in both Barb's and Will's bodies are a larval stage, perhaps).  Barb died (whether by Demogorgon violence or just toxic atmosphere, we don't really know), but she wasn't eaten.