Stranger Things creators say season 5 will finally reveal "what the Upside Down actually is" after "purposely" holding back for "almost 10 years": "We really wanted the show to come full circle"

After four seasons spread out over almost 10 years, Stranger Things creators Matt and Ross Duffer are finally ready to explain the mysterious origins of the Upside Down.

“When we pitched to Netflix, we knew that they weren’t interested in a limited series, so when we were making season one, we knew that in success, it would continue, and so we purposely held back certain mysteries," Ross told SFX Magazine. "The biggest one from season one was about what the Upside Down actually is, which is something we’ve known now for almost 10 years. We’ve thought about revealing it every time we write a season, and we just kept holding it back and holding it back. It was exciting this season to be able to finally reveal what the Upside Down is, and it plays a huge role in the narrative, that final mystery of what it is, and what it all means.”

Though the Upside Down began as an alternate dimension crawling with dangerous creatures, season 4 deepened the lore and explained that although the Upside Down was technically created in 1983 (thanks to Eleven), there are several alternate dimensions – one of which Henry Creel, aka Vecna, found himself banished to in 1979. The Upside Down opened up, a mirror copy of the human world, appeared after Eleven accidentally opened the Mothergate in season 1 (when Dr. Brennan, aka Papa, pushed her to make psychic contact with the Demogorgon). Though that gate was eventually sealed, the Upside Down continued to grow, and more gates continued to open.

At the end of season 4, we see the Upside Down spill out into Hawkins and take over the sky, killing all of the vegetation and blocking out the sun. It's kind of wild to think that, after seeing the latest Stranger Things season 5 trailer, Mike, Dustin, and co. have to go back to school while there's a physical evil encircling the entire town.

But as for what all of these alternate dimensions are, where the Demogorgon and Mind Flayer came from, and how one of the dimensions was able to take Henry Creel and turn him into Vecna...we still don't know. Thankfully, season 5 will finally tell us.

"From season one onwards, we’ve tried to put everything out there,” he continued. "We always try to make the coolest season possible, and with the exception of holding back on the Upside Down, we try to put everything on the table. We view each season more as a long-form movie. Not that we’re not taking mythology into account, or the slow-drip reveal of the mythology, but the focus has always been to try to tell the best story we can."

The fifth and final season sees the gang trapped in Hawkins under military quarantine in Hawkins: nobody in and nobody out. In the trailer, Mike, Eleven, and co. form a plan to hunt Vecna down once and for all...but it doesn't look like we're going to get a happy ending.

Added Ross: "Most mysteries that have been unresolved so far in the show are related to the Upside Down. To finally be able to reveal all that was very satisfying. And it leads to some pretty spectacular set-pieces and visual effects that we’re really proud of."

Stranger Things seasons 1-4 are streaming now on Netflix. While we wait for Stranger Things season 5 to premiere on November 26, check out our picks of the best Netflix shows for some viewing inspiration.