Supernatural's teaser for their midseason finale has fans as nervous as ever.

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To ease your minds, here is what we know about "The Things We Left Behind"

Claire Novak Will Return

The daughter of Castiel's (Misha Collins) vessel is back in the picture. Now a punk-rock teen living in a group home, Claire will convince Cas to break her out, but the youngster will quickly run off.

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It's going to be a great little arc," Collins teased, according to She Knows. "I don't even know how little the arc is or how big it is. We, so far, are doing two episodes that focus [on Claire.] It's the midseason finale ["The things We Left Behind"] and midseason premiere ["No Place Like Home"]. Those two episodes are going to focus on, not exclusively, but a big centerpiece of those episodes is going to be the relationship between Claire and Cas."

Dean Will Make A Decision About The Mark

"Dean finally makes a decision about the troublesome Mark of Cain plaguing him," TV Line teased.

"Hibbing 911" marked the first time Dean (Jensen Ackles) didn't feel the effects of the Mark of Cain while killing, but the brand will rear its ugly head in a major way during "The Things We Left Behind." If the promo is to be trusted (they often mislead viewers), Dean will have plenty of blood on his hands by the end of the episode, and Castiel will have a deadly promise to keep.

There Will Be A Twist

"This episode has a huge twist at the end!" tweeted S.E. Hinton, Supernatural fan and author of Outsiders, while on set for filming.

Director Guy Bee ("Stairway to Heaven," "Devil May Care") has also earmarked the midseason finale as an "odd" episode.

Find out more when Supernatural airs Tuesdays at 9 p.m. ET on The CW. Scroll through the photos above and click the video below to get a look at "The Things We Left Behind."