‘Supernatural’ Season 10 Spoilers: Episode 9 Synopsis Released; What Will Happen In The Midseason Finale, ‘The Things We Left Behind’?

He’s back! Demon Dean (Jensen Ackles) will be reprising his dark role in Season 10 of “Supernatural” when the CW series airs its midseason finale on Tuesday, Dec. 9. A promo video for episode 9 teased the news when Dean requests a favor from Castiel (Misha Collins) that’s so terrible we still have goosebumps thinking about it.

“I need you to promise me something. If I do go dark side you gotta take me out,” Dean says in the trailer for “The Things We Left Behind.”

The eldest Winchester brother then goes off on a tangent, listing off way Cas can kill him if he turns into the demonic creature. “Knife me, spike me, throw me into the freakin’ sun – whatever,” he said. “Now don’t let Sam (Jared Padalecki) get in the way, because he’ll try. I can’t go down that road again, man.”

Cas then questions his supernatural-hunting friend if the Mark of Cain is still affecting him, which Dean replies with, “I can’t be that thing again.” And we don’t blame him. Dean did some pretty awful things as a Demon; from killing an innocent client to nearly murdering his own flesh-and-blood.

But according to the promo video, Dean will be going rogue despite his plan to avoid turning dark-eyed. In the trailer, viewers see Dean covered in blood and kneeling in a room full of dead people.

But Demon Dean drama isn’t the only storyline viewers can anticipate in episode 9. According to the synopsis, Castiel will find Jimmy’s daughter Claire (Kathryn Love Newton) “in a group home,” where she’ll use her wit to convince Cas to break her out.

After she runs away from him, Castiel calls on the Winchester brothers to help find the girl before she “gets in trouble.” While Sam and Dean get put on detective duty, “Crowley (Mark Sheppard) faces his biggest challenge yet.”

What do you think will happen in the Season 10 winter finale of “Supernatural”? Sound off in the comments section below with your predictions and make sure to tune in to episode 9 on Tuesday, Dec. 9, at 9 p.m. EST.