Sam stares at the ceiling of the hotel room. Today's hunt was exhausting, but he can't sleep. He is worried. That's why he just lays here and listens Dean's breathing in the dark, as if to be sure that his brother is still alive.
Dean is dreaming. Sam can hear him mutter.
A single word. Barely recognisable, if you don't know how to listen.
It's a name. Sam thinks it is forgoten a long time ago. A name Sam hasn't heard spoken out loud for years. A name that once meant so much.
"Cas..."
And Sam knows what his brother is dreaming about.
The night The Darkness was defeated.