An ending worthy of Castiel
Cas tells Dean he’ll wait for him.
What’s a few years or even decades for an angel who faces eternity?
In the meantime, Cas returns to heaven in order to make amends and find peace that has eluded him for ages. While there, he plans to carve out a spot where Dean can one day join him. One day, that is, when Dean is ready to lay down his Hunter’s burden.
Until then, Castiel rests. The lives of the Winchesters have brought him too many sorrows.