Season premiere of "Supernatural" gave Jensen Ackles' character of Dean some time to enjoy being a carefree demon by drinking, bedding waitresses and killing other demons. But towards the end of the episode, a new enemy arrived who has put his brother's life at risk, and the Winchester brothers are back to saving each other's lives.
And as the season progresses, the Mark of Cain can prove to be a problem. For instance, in the second episode of the season, Dean becomes more aggressive and believes it to be the side effect of being a demon, but Crowley realises that Dean's aggressive behaviour can be controlled only if the Mark of Cain is fed.
"It's kind of a demon on steroids," Ackles told Entertainment Weekly on demon Dean with the Mark of Cain. "It's like a super demon. I think that he doesn't necessarily know how to control it as a human, and he doesn't even know how to control it as a demon, and that will continue to be a problem as the season goes forward."
However, Dean being a demon won't be the biggest worry this season, although making Dean a human will be the central plot of the first half of the season. Castiel's fading grace will be a cause of concern, and as per the synopsis of the second episode, Hannah makes a bold choice and asks Metatron for help.
Metatron has the cure to Castiel's problem, but it remains to be seen if the angel will work with Scribe of God, as he was the one who took away Castiel's grace in the first place.
As for Dean's future, Ackles said that his character will eventually be saved, and the Winchester boys will be back to hunting down the supernatural.
"The boys are back together, they're on the road, and they've kind of got to bridge that gap that's kept them so far apart over the past year—from the possession of Gadreel to Dean going dark side and being with Crowley," said Ackles.
"And then also, I've got to think of what Sam had to do or what he's trying to do to get his brother back. He might tend to go a little dark. He gets pretty desperate, so there's a lot of bridging gaps to be done once that situation does rectify itself. But once that happens, then of course, there's gotta be something on the horizon for more of the characters involved," he added.