'Stranger Things' season 2 spoilers, plot news: Eleven exists in another form?; series possibly delves into Hopper's past

David Harbour as Hopper in "Stranger Things"Facebook/StrangerThingsTV

Eleven (Millie Bobby Brown) is returning in season 2, but she might no longer be in human form. Meanwhile, the series might try to unearth Sherriff Hopper's (David Harbour) mysterious past.

Previously in "Stranger Things" season 1, the young heroine Eleven used all of her energy and powers to destroy the demogorgon that was about to devour Mike (Finn Wolfhard) and the rest of Hawkins. After she saved the town, Eleven disappeared and there was no proof that she was still alive.

However, it was recently announced that Eleven is coming back in "Stranger Things" season 2 when a photo of the cast during a table-reading was posted upside down on their social media accounts.

In an interview with The Daily Beast, Harbour explained that Hopper knows that Eleven still exists, but she may be living on in a different form. Harbour referenced the season 1 finale where he went somewhere with the Hawkins lab people, and a month later, he was seen leaving Eggo waffles in the woods for Eleven.

"Whatever's going on with the lab, Hopper's involved a little more deeply than we realize. And part of that may be that he has some sort of understanding of this upside down world that other people don't have. And in that way, he may understand that Eleven exists in some form," explained Harbour.

Meanwhile, "Stranger Things" season 2 might go deeper into Hopper as a character.

Hopper's past was revealed in season 1, and through flashbacks, viewers saw that he lost his young daughter due to cancer. Harbour said that he has discussed Hopper's backstory with the Duffer brothers. The actor and the brothers talked about the character's guilt and how he died inside when his daughter died, and that there is a lot more of it to tell.

"There are little Easter eggs throughout. So I don't want to give too much away, but I will say there is more onion to be peeled back in terms of Hopper's backstory and what he's been through. And his daughter's cancer was a lot more complex than what it seemed," added Harbour.

"Stranger Things" season 2 is set to debut in 2017.