Sam and Dean's pasts will come to bite them in the butt during Supernatural's season 11.

'Supernatural' Season 11 Spoilers: Castiel & Crowley Have 'Far Bigger' Problems Than The Darkness, Jeremy Carver Teases Premiere

The Darkness is out in the world, and the new big bad will somehow call on the Winchester's past successes and mistakes as it seeks to wreck havoc on the world.

"You can't outrun your past," executive producer Jeremy Carver teased, according to TV Guide Magazine.

'Supernatural' Season 11 Spoilers: The Darkness Is The Biggest Threat Since Lucifer? Jeremy Carver Teases New Evil

Carver's statement is fairly enigmatic, but Mark Sheppard (Crowley) cleared up the concept ever so slightly while at Nerd HQ on Sunday.

"When they are reduced to their lowest common denominator, they always do the right thing. They always pick the path - sometimes the hardest path - but they always try to save, they try to make better. They try not to make worse," Sheppard explained. "And yet, what they are going to pay for in season 11 is the choices they made at the end of every other season so far...There's a cost to it all."

Well, that certainly sounds ominous. Supernatural has yet to reveal exactly what the Darkness is (see video below), other than the fact that it is pre-biblical, and the cast's cryptic teases are sure to have fans scratching their heads all summer.

Find out more when Supernatural returns to The CW on Oct. 7 at 9 p.m. ET.