'Supernatural' New Season Will See Arrival of a Surprise Guest - A Demonic Dean

(Photo: CW/File)

"Supernatural" Season 10 is expected to thrill fans with many new developments in the show, including Dean (Jensen Ackles) embracing life as a demon. The end of season 9 shows Dean dying, but the Mark of Cain was able to resurrect his as a demon. Executive producer Jeremy Carver said that the new season begins with Sam (Jared Padelecki) going on his own journey in an attempt to find his missing brother.

"Sam is so invested in finding his brother that it leads him to do some questionable things that will make him, and certainly, the audience wonder which one of these guys is the true monster," Carver told TVLine.

Moreover, Carver said that Dean's switch to demonhood is rooted in the mythology of the show and that when he changes back, it's not going to be a clean break.

"Dean being a demon here ties into a deeper mythology in the show, that being the Mark of Cain and Cain … It wasn't so much the spectacular effect or whatever of Dean being a demon. It's more just rooting him in something more final, something that will not necessarily totally go away even when/ if he's converted back from demonism," he explained.

The show will also welcome back some familiar faces like Kim Rhodes as Sheriff Mills and Brianna Buckmaster as Sheriff Donna Hanscum.

Carver also said that a mystery guest will be seen in the new season. "We'll see one other character that we introduced a couple seasons ago who I don't want to spoil just yet."

In addition, the 200th episode will feature a "musical-ish" episode which will feature "just about every character—I'll say that they will be represented—that you've ever loved or hated on the show, and I say that very obliquely on purpose," teases the show runner. "So they will be there in spirit."

'Supernatural' Season 10 will premiere on October 7 on The CW.