There is just one more day to go before the big season 10 premiere of "Supernatural," and fans are eagerly awaiting to see if and how Sam is going to deal with the fact that his brother has turned into a demon.

Going by season 10's spoilers, each of the main characters are going to have a difficult journey that will make them the main villains of the upcoming season.

As the Winchester boys battle their inner demons, the show will be "be introducing, over the course of the season, characters that are very, very, very personal to our main characters," executive producer Jeremy Carver told TVLine, adding that it's all going to "snowball into, 'You are who you are,' and having to deal with all this and drawing some lines. Of course, there'll be Bigger Bads that emerge, but the central focus of the season is really on these personal arcs."

The season premiere will show Dean adjusting to being a demon by womanising and hitting the bottle hard, while Sam struggles to find a way to bring Dean back. But his brother clearly does not want to be saved.

And this will lead to unlikely alliances. For instance, in episode three titled "Soul Survivor," Crowley realises that Dean being a demon is not working out in his favour, and the King of Hell finds an unlikely ally in Castiel.

The premiere episode is titled "Black" and according to the synopsis Dean will be living it up as a demon while Sam hits rock bottom in his search for Dean. In "Reichenbach," the second episode in the series, "Crowley (Mark Sheppard) notices Dean (Jensen Ackles) is becoming more and more aggressive. Dean tells him that's the side effect of being a demon, but Crowley knows it's something more - the Mark of Cain needs to be fed."

Season 10 will also see the return of a character from the fourth season in the form of daughter of Castiel's vessel Jimmy Novak. Claire Novak, a 17-year-old, is said to be an angry teenager who is sarcastic, smart and defiant because of her rough past, according to E!Online.