Tonight is the season 10 finale of the show Supernatural, starring Jared Padalecki and Jensen Ackles. The finale episode of the season is titled “The Things We Left Behind” and the synopsis reads:
When Castiel finds Jimmy’s daughter in a group home, she persuades him to break her out; Crowley is faced with a big challenge.
In a clip from the finale:
It shows Dean having a vision of himself covered in blood when Castiel asks the Winchester brother if the Mark of Cain was still affecting him. Dean then extracts a promise from Castiel that he would take him out if Dean ever goes over to the dark side.
Dean warns not to let Sam get in the way. Will Castiel have to kill Dean?