Eleven (Millie Bobby Brown) is still missing, and she might also have a missing brother. Meanwhile, Will (Noah Schnapp) will attempt to live a normal life while seeing images of the Upside Down.

"Stranger Things" season 2 is expected to premiere this October on Neftlix, and the biggest mystery that is anticipated to be unveiled is the whereabouts of Eleven and how she survived the blast of energy from defeating the Demogorgon.

However, there might be another mystery tied to the story of Eleven. As confirmed by series co-creator Matt Duffer to Entertainment Weekly, Eleven's back story will be tackled in "Stranger Things" season 2.

This was tied to one of the show's episode titles, which might be hinting at Eleven having another family member introduced in the series. According to Mashable, episode 9 of season 2, titled "The Lost Brother," might be hinting at Eleven's missing brother.

However, this is just speculation, and details that tie Eleven to having a sbiling has not been confirmed on the show.

Meanwhile, "Stranger Things" season 2 will see Will Byers struggling to live a normal life while having flashbacks and visions of the Upside Down.

According to series producer Shawn Levy, it is everyone's desire in Hawkins to return to having a normal life, most especially the Byers family, Collider confirmed. However, it will be impossible since Will is constantly exposed to the Upside Down, and more monsters are coming out of the alternate dimension.

However, Matt pointed out that Will's visions of the Upside Down might not be real, and they might only be created by his imagination, Digital Spy reported. This will probably be the reason for Will being examined by a doctor with tubes connected to his head, as seen from the Super Bowl Ad. They might be doing so to find out if his visions are real or not.

"Stranger Things" season 2 is set to premiere on Oct. 31 on Netflix.