The Voice (Castiel Original Story)

Dean and Sam had ultimately met their matches with life-- Dean with an unavoidable heart attack at the ripe age of 72 and Sam with a long and well-fought battle against bone cancer at the age of 74. Evil still wreaked havoc, only stalled momentarily by the death of the legendary Winchesters. It was as if the world expected him to continue being Cas after he had just lost his favorite humans, the ones he fought so hard for. Castiel, Angel of the Lord, was not about to move on from the boys so quickly.
He could never expect to find the will to fight alongside anyone but them. He had imprisoned himself, helping no one, and eventually warding his mind off from being reached by the cries of other hunters in peril, by his Father, by his brothers and sisters, by life itself.
But he also didn't expect someone to break the barrier and talk to him every night for 12 years. 12 years that passed in utter silence aside from her constant rambling, a train of thought with no track. Why couldn't he fall from Grace in peace?