On this week's episode of Supernatural...
Balthazar changes history by stopping the Titanic from sinking. This creates a domino effect where the people onboard survive, Ellen and Jo are alive, and the boys drive a Mustang.
Fate tries to course correct this change by killing off family members connected to the sinking ship. She also sets her sights on Sam and Dean because they stopped the apocolypse.
She reveals that she knows Castiel sent Balthazar to save the ship in order to gather more souls for his war machine. He spares her life in order to save the brothers from death.