“Supernatural” already introduced Cain in season 9, but how about his errant brother Abel? New spoilers about the upcoming season reveal Sam going dark, Castiel hunting Dean, new character Cole getting a significant role, the biblical Abel making an appearance and how “Carry On My Wayward Son” is involved in the musical-ish episode.

Exec producer Jeremy Carver has generously spilled spoilers from the upcoming season to Entertainment Weekly, giving viewers some insights on what will happen to the brothers and their angel friend.

So far, as was teased at the Comic Con, fans already know that Demon Dean (stylised as Demon!Dean by the online fans) will be having a one-on-one killing session with Sam, and it’s heartbreaking!

Sam (Jared Padalecki) will be looking for Dean (Jensen Ackles), who, unbeknownst to him, has been turned into a demon at the season 9 finale. He will soon find out that his dead brother isn’t dead at all.

He isn’t the only looking for Dean, though.

“... four to six weeks after Dean’s eyes first went black,” another character named Cole will be joining the story. Cole isn’t the typical hunter viewers are used to. He will be hunting down Dean for entirely different reasons than Sam’s.

“It’s going to cause all kinds of complications, and the character of Cole is someone who will evolve from how we see him to something very different once he finally does come face-to-face with Dean,” exec producer Jeremy Carver told the Web site.

Sam will also face a role reversal with his brother. The younger Winchester brother has always been the reluctant hunter who has had Dean to protect him from danger.

In season 10, that will change.

“I think historically, Sam has been the brother that has gone around the bend a little bit – when he became a demon with the demon blood and everything – so picking up from last season, Sam finds himself in something of the position of protector. That’s a bit of the flip for the boys,” Carver explained.

“It’s something that Sam takes very seriously coming into this season while also having to deal with some of the things he did, which are morally questionable, while on the hunt for Dean.

He added that Sam, who became morally questionable when his soul was left behind in the pit, will turn “pretty dark” this season as well.

Apart from Sam and this new Cole character, Castiel will also be looking for Dean. But although it should be obvious that the dying angel should partner up with Sam, he won’t.

“There’s more than one reason that Castiel (Misha Collins) and Sam are not together on the search for Dean at the beginning of the season,” Carver teased. “One has to do with Castiel not wanting to be a distraction with his own issue, and there’s another reason which we learn during the episode.”

Castiel’s issue being his fading stolen grace, which will effectively kill him once it has diminished, and it’s diminishing fast.

As Collins has said in previous interviews, Castiel is already resigned to dying. His main mission is to “fix” Dean.

It’s not as if Sam can just exorcise his brother and things will be well just as before. As fans have pointed out, Dean isn’t possessed; he’s a demon himself. The Mark of Cain is still very much present in his person, and this makes turning Dean back to human a challenge.

“It’s still around, and it’s very much a question for the first run of episodes if it still has an effect on Dean or not. And it’s very much on the boys’ minds as they plot out a game plan for the next batch of episodes after Dean is healed. In other words, the boys are very much focused on healing their relationship and healing one another.”

Carver would love to have Cain (Timothy Omundson), who gave Dean the Mark of Cain, return on the show, but Omundson is already busy shooting the new show “Galavant.”

So Cain’s reappearance on the show is uncertain, but how about Abel? The biblical brothers’ story was given a twist in the show, with Cain actually being the sacrificing older brother for his demon-dealing younger Abel.

It turns out the writers of the show have discussed Abel.

“That’ a great idea, and [it] has been bandied about in the writers room,” Carver said of Abel’s appearance.

It was previously reported that fan favourite Sheriff Jody Mills (Kim Rhodes) and Sheriff Donna Hanscum (Brianna Buckmaster) are returning in the show. Another character who has been introduced a couple of seasons past will also make a comeback, though Carver refused to name him or her yet.

Read: ‘Supernatural’ Season 10 Spoilers: Sheriff Jody Mills to Return

As for the highly anticipated 200th episode special, or also known as the “musical-ish” episode, the theme song “Carry on My Wayward Son” by Kansas will be in the episode “in one form or another.”

Read: ‘Supernatural’ Star Jared Padalecki: Musical-ish Episode Will be Based on Chuck’s Books + Jensen Ackles’ ‘Nude Scene’

“Supernatural” season 10 will premiere on October 7 in the U.S.