[s4e21] When The Levee Breaks -

: Dean tracks Sam to a motel, leading to a violent brawl. After Sam nearly strangles him, Dean delivers a final ultimatum: if Sam walks out the door, he should never come back. Sam leaves, effectively severing their bond as they head into the finale. Major Character Dynamics

: Ruby reveals that Lilith is "Lucifer's first" demon and that only she can break the final 66th seal. [S4E21] When the Levee Breaks

: Directed by Robert Singer and written by Sera Gamble. It is one of only three episodes in the entire series where no characters die. : Dean tracks Sam to a motel, leading to a violent brawl

: Faces internal conflict after being ordered to sabotage the brothers' efforts, ultimately capturing Anna Milton when she confronts him about his actions. Lore and Production Details [S4E21] When the Levee Breaks