On clear nights as they drove across the country, Dean and Sam would pull over on the shoulder of a backroad and stare up at the heavens, cataloguing constellations and chatting back and forth about the mythology behind them. The stars felt distant and protective, a blanket swaddled around the earth.
Dean's favorite constellations were Ursa Major and Ursa Minor, because of the way they came to be. Ursa Major was originally a nymph named Callisto who was turned into a bear by Hera, the jealous wife of Zeus. Her son Arcas was a hunter and he tried to kill her, so Zeus tranformed them into stars to save her and immortalize them. Sam's favorite was Cassiopeia, at first because it made a W in the sky, and later because he learned that when the main star, Gamma Cassiopeia, finally burns out, it will cause a massive supernova.
The stars were their constant companions, the only thing that had been there their entire lives, following them from state to state and winking encouragingly when they allowed their gaze to stray upward. Dean stared up at the sky now, and felt more alone than he ever had in his life.
There were no stars to break up the velvety blackness of the sky in Purgatory.