Casey

Casey was a bartender in a small town in Ohio that was plagued by vice. When Dean saved a man in her bar, she flirted with him a little before he left. She later took Dean's friend Richie to the house her parents left her, where she killed him, revealing that she was in fact possessed by a demon. The next day she brings Dean there instead, intending to kill him too, but he was a step ahead of her: having tracked the GPS in Richie's cell phone, he found the house, buried Richie, and made a Devil's Trap in the floor. He tried to banish the demon before she caused a small earthquake, scattering the pages of the exorcism book and trapping Dean down there with her. The two enemies decided to be civil with each other as they were at a stalemate (Dean cannot banish her without his book and she cannot hurt him while in the Devil's Trap), and struck up a conversation. Eventually, the two reach a sort of friendship, or at least tolerance. Casey respects Dean's deal and Dean regards her with a tolerance he does not afford demons. Dean calls her evil, to which Casey responds that she did not kill anyone, simply saying that one can "nudge humans in the right direction and they’ll walk right into hell with big fat smiles on their faces". Casey identified herself as a true believer in Lucifer, comparing him to the Christian's God, and told Dean the Yellow Eyed Demon's name, Azazel, and that Sam was supposed to lead the demon army.

Father Gil ended up arriving first, having left Sam upstairs. She kissed him passionate and told Dean they had been lovers for centuries. When he wanted to kill Dean, she quickly begged Father Gil not to before Bobby charged in with the Colt, killing him. Dean similarly begged Bobby not to kill her, but he was too late.