Steve will die.
First introduced as Nancy's jerk boyfriend, Steve pivoted to fan favorite in season two of the show, thanks in large part to his stint as the world's best monster-hunting babysitter. Steve's unlikely friendship with Dustin has also been one of the most endearing plot points of the show so far, and that bond is shown to still be present in the trailer. But the character's newfound popularity has now got fans worried that he might end up biting the dust in season three, as Stranger Things has a habit of killing off people who are "too nice"; just look at poor Barb and Bob. Losing Steve after such a turnaround would certainly pack an emotional punch.
Billy will become even more of a monster.
Season two gave the young gang a new member in Max, but it also brought the show a new secondary antagonist in Billy, her abusive older brother, who replaced Steve as Hawkins' resident bully. It looks like Billy will have an expanded role in the third season: the trailer shows him in the shower with some kind of infection, similar to what Will has suffered, prompting speculation that Billy will undergo some kind of hideous transformation, and he might actually end up being the show's next big monster.
The Upside Down is actually the future.
One of the central mysteries propelling Stranger Things is the Upside Down, a shadowy alternate universe populated by hideous creatures which keep making their way into 1980s Hawkins. Season one revealed that Eleven's telekinetic powers were what opened the rift between worlds, and season two saw her close the gateway: but what if the Upside Down isn't another dimension, but another time? "Eleven has serious psychic powers that the US government was testing as a weapon," writes Ani Bundel at Elite Daily . "What if, in their testing Eleven tore a hole through space and time, and what were seeing is Hawkins future? One where the town underwent a nuclear holocaust in order to well, prevent residents from passing through time?"
We'll hopefully get some answers when season three of Stranger Things hits Netflix on July 4.