As we've still got a little while to wait until our questions are answered, we've scoured the depths of internet fandom to find the most plausible - and entertaining - theories and predictions for what could happen in the new season.
Immerse yourself in the below, and remember to high five us if any actually come true.
Theory 1: That’s not the real Will
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A number of fans on Twitter and Reddit have suggested that Will is still trapped in the Upside Down, and that the worm-spewing young lad who arrived home to his pals is actually an impostor – which is a rather unsettling thought. Redditor Ndeg4 points to the ease with which Joyce and Hopper retrieved Will from the Upside Down, and the fact that Dr Brenner explicitly told them that they wouldn’t find Will. Was he telling the truth? Did they actually bring a monster back home with them?
Alternatively – and perhaps more plausibly – Will has returned from the Upside Down... but has brought something back with him. We'll discuss this possibility in more detail below.
Theory 2: The red tentacle monster coming towards Will in the trailer is… Barb!
This one may be wishful thinking rather than logic, but it is the theory that has most fans talking.
After Barb was so cruelly dispatched in season one as her supposed BFF Nancy got intimate with Steve upstairs, viewers were fuming. The last we saw her, she was a rotting, worm-ridden corpse in the Upside Down. But some fans are suggesting that the red, tentacled monster that appeared in the 30-second trailer is some form of “Mega Barb”, back to take revenge on the people of Hawkins, Indiana who failed her.
But before you get all excited for #JusticeForBarb, remember that the creators have pretty unequivocally said that Barb is dead and gone (see the clip below), despite hinting that she may get her just desserts at some point.
“Some doors can’t be closed” clearly alludes to the portal between Hawkins and the Upside Down, and one theory on Reddit suggests that Mega Barb is caught in it, straddling the boundaries between both worlds.
We can be fairly certain that the portal remains open, as the Duffer brothers suggested in an interview with Entertainment Weekly last summer.
“We obviously have this gate to another dimension, which is still very much open in the town of Hawkins,” Ross Duffer said. “And a lot of questions there in terms of, if the Monster is dead, was it a singular monster? What else could be out there? There’s a lot more mystery there to be solved.”
Theory 4: The new monster is another Dungeons and Dragons-esque creature
Ok, so it’s probably not Mega Barb after all. Given that Dungeons and Dragons lore played such a big part in season one, fans turned to the role playing game to look for clues about other terrifying prospects lurking in the Upside Down.
Even before we got our first glimpse of the beast in the post-Superbowl promo, the Thessalhydra, an eight-headed monster from the game had been suggested as a possible danger for season two - the monster actually featured in the closing scenes of season one.
And the shots from the trailer, though not exactly matching the game's description, seems to have backed this idea up. The massive multi-limbed creature, seen peeking out amongst eerie red clouds and in a drawing (presumably by Will, who appears to be the one who sees the monster) is certainly worthy of the nickname at the very least.
Other fans point out that the monster's D&D origins include the fact that the Thessalhydra reproduces by infecting hosts with larvae – which doesn't bode well given that Will is seen coughing up slugs at the end of season one. Poor kid can't catch a break.
The Thessalhydra is able to regenerate its heads after they are cut off. The only way to defeat it is to cut all eight off at once. Crucially, in the D&G scene in season one Mike says they only cut off seven heads. The job is not finished.
Even the way to defeat the Thessalhydra is very Stranger Things: with multiple heads, it cannot be defeated by a single opponent. Only by joining forces can all eight heads be decapitated at once. What does Stranger Things teach us? It takes teamwork to defeat the baddies...
Theory 5: The Upside Down is Hawkins, Indiana in the future
Redditor Alice4223 has put forward the ambitious idea that the barren, inhospitable environment in the Upside Down is an alternate reality, in which the Cold War resulted in a wide scale nuclear holocaust, and that the monsters are people mutated by radiation. This would explain why some of the elements bear a resemblance to the real world – such as Steve’s pool, where Barb was murdered.
Others have suggested that the nuclear holocaust version of Indiana is a not-too distant future, and that Eleven opened up a space-time continuum which has allowed bits of the future world to bleed into the present day. Either way, the freaky Cold War era parallel is a neat way to link the show's sci-fi horror with its political context.
Theory 6: Hopper has turned to the dark side
Last time we saw Hopper, he was getting into a car with some pretty shady-looking government agents. The Duffer brothers and actor David Harbour have already confirmed that he will be making a huge effort to hide the events of last season from the people in Hawkins, which may involve covering up poor Barb’s disappearance in some way.
Plus, the fact that Joyce has a new love interest in Sean Astin may suggest that the role of heroic father figure may be filled by someone else this time around. So, while it’d be a tough one to take, it’s entirely plausible that Hopper is working with the feds, whether under duress or of his own accord.
Get the low down on everything we know about the new season here.
Stranger Things season 2 arrives on Netflix on Friday 28th October 2017