'Stranger Things' Season 3: 5 Upside Down and Mind Flayer Rules to Remember

Stranger Things is poised to return for on July 4, bringing excited fans back into the world of Hawkins for Season 3. Now set during the summer of 1985, the residents of Hawkins will be faced with the threat of the Upside Down taking over their world once again, along with the uber-creepy Mind Flayer from Season 2.

While it’s impossible to refresh on every aspect of Stranger Things before you dive into Season 3, we thought it’d be worth recapping all the big rules about the Upside Down and the Mind Flayer. This alternate dimension and the unusual being lording over it have the power to change life in Hawkins as we know it. Don’t you want to know who your favorite characters are fighting?

Let’s take a look. Here are five important rules about the Upside Down and the Mind Flayer, plus definitions of what those things actually are.

Possible light spoilers for Stranger Things Season 3 ahead.

What Is The Upside Down?

The Upside Down is an alternate dimension of unknown age and origin. A portal between the dimensions was opened by Eleven when she psychically connected with a Demogorgon in Season 1. The Upside Down looks like Earth, with similar landmarks and elements like light, sound, and gravity adhering to the same rules Earth is used to. However, there is a severe state of decay pervading the Upside Down, with membrane-like flora covering various surfaces and spores of mold or bacteria of some sort floating in the air.

What Is The Mind Flayer?

Named after a Dungeons & Dragons character of the same name, the Mind Flayer first appears as a large shadow monster in the shape of what looks like a spider. It seems to control all life in the Upside Down through a hive mind, sending Demodogs into Hawkins and controlling Will in Season 2. It’s not clear how old the Mind Flayer is or if there are more like it in the Upside Down.

5. There Are Two Ways to Enter the Upside Down (That We Know Of)

Stranger Things Season 1 and 2 established that there are mainly two ways you can enter into the Upside Down. The first method is to physically enter through a portal between dimensions. The second is to be transported there psychically.

Humans, including Will, Barb, Nancy, and Eleven, have physically entered into the Upside Down in the past. Characters can be brought back into the dimension after interacting (willingly or unwillingly) with a creature from the Upside Down like the Demogorgon. Physical entry consists of going through a portal created between the two worlds. In Season 2, it’s implied multiple portals exist all across Hawkins, as shown when Nancy entered through a new portal in the woods outside Hawkins while Eleven pushed her way through a temporary portal at Hawkins Middle when she was stuck in the Upside Down at the beginning of Season 2.

It’s also possible to be psychically transported to the Upside Down, like what happened to Will in Season 2, but this seems to only work if you’ve already spent time there. Will was pulled into the Upside Down through life-like visions, making it possible for him to move around in that dimension while his body remained in Hawkins.

4. Anyone Can Travel to the Upside Down

There are no special requirements to enter into the Upside Down, so come one, come all! All you have to be is a human with a beating heart and an endless well of curiosity about what awaits you in this hellish dimension.

3. Don’t Stay in the Upside Down Too Long

If Will’s time in the Upside Down has proven anything, it’s to not stay there for too long. Unlike Nancy’s time in the Upside Down, which was only for an hour or two maximum, Will spent at least a week in the Upside Down.

He came home a much-changed young man, coughing up what looked like slugs and frequently unable to focus when he was with his friends. It’s believed the spores seen floating around the Upside Down as well as the environment take a toll on the human body and send it into a slow deterioration. 

2. the Mind Flayer Controls Everything and Anything It Wants

As the sentient ruler of the Upside Down, the Mind Flayer is able to control the consciousness of any being it chooses. In the Upside Down, that means the Mind Flayer can control the Demodogs and communicate with the rest of the environment, bending it to its will. Oh, and speaking of wills, the Mind Flayer proved it’s the ultimate Stranger Things villain when it possessed Will’s body in Season 2 after pulling him into the Upside Down through his mind and taking over his body. It took a lot of work from Will’s friends and family to free Will of his attachment to the Mind Flayer, but that doesn’t mean the monster is done possessing Hawkins’ residents.

1. Eleven Is the Only Person in Hawkins Who Can Stop the Upside Down and the Mind Flayer

Seasons 1 and 2 have made it clear that the only character equipped to tackle the creatures and creeping domination of the Upside Down in Hawkins is Eleven. As the person responsible for making first contact with a Demogorgon while she was being experimented on in Hawkins Lab (revealed in Season 1), Eleven has always been intimately connected psychically to this alternate dimension. When it came time to close the primary portal between the Upside Down and Hawkins in Season 2, Eleven was the only person with the ability to make it happen.

Of course, Eleven isn’t the only superhero in this world. As we learned in Season 2, there are other survivors from the same experiment, including Kali. But when it comes to the residents of Hawkins, Indiana, Eleven is our only hope.

Stranger Things Season 3 premieres on Netflix July 4, 2019.