A brilliant, hilarious meta-episode where the Trickster (Gabriel) traps Sam and Dean in various TV show parodies.

, triggered by the release of Lucifer from his cage at the end of Season 4. The Core Conflict: Destiny vs. Free Will

Sam spends the season grappling with his addiction to demon blood and his guilt over killing Lilith (which broke the final seal). He says yes to Lucifer momentarily to trap him, showcasing the ultimate self-sacrifice. The complete season shows Sam’s slow descent into nihilism and his ultimate redemption.