like Dean so that, if he fails to save Dean's soul, he is ready to face a world full of demons on his own. Season three also sees the introduction of the demon Ruby, who tries to gain Sam's trust by helping the brothers in fixing The Colt, saving them numerous times, and telling Sam she can save Dean from Hell, even though in reality she cannot. Ruby also reveals that because Sam refuses to lead the demon army, another demon named Lilith has filled the power vacuum and is leading the army while carrying intentions to kill Sam; she is also revealed to hold Dean's contract for his soul. In the season finale, Sam and Dean, armed with Ruby's demon-killing knife, confront Lilith in a last-ditch effort to save Dean's soul. Sam is incapacitated by Lilith and forced to watch as his brother is killed by a hellhound. Lilith then tries to kill Sam; however, her powers have no effect on him and she flees, leaving a crying Sam with Dean's mutilated corpse. Season 4 Four months after the season three finale, Dean wakes up in his own grave and claws his way out. He and Bobby meet up with Sam at a motel, where an overwhelmed Sam joyously reunites with Dean. While trying to figure out how Dean returned from Hell, Dean and Bobby confront the being who revived him, Castiel, an angel who was ordered by the Archangel Michael to raise Dean from the fires of hell and resurrect Dean. They discover that this happened because the angels need Dean and Sam's help to stop Lilith, who is breaking the 66 Seals of God. Once the Seals are all broken, Lucifer, the first fallen angel and chief adversary in the war of angels and demons, will be freed from Hell, bringing the Apocalypse upon the Earth. It is also revealed that Lucifer spawned all of the demons starting with Lilith who is now active. Castiel develops a friendship with Dean and helps him understand the upcoming events. Castiel also reveals the Winchesters' past and shows Dean the connection between the now deceased Demon Azazel and his family. He reveals that Dean's mom was a hunter and working cases around the time Azazel was making crossroad deals in 1973. She and her hunter family, the Campbells, tracked the yellow eyed Demon down and eventually the Demon was stopped,