He didn’t say much as the reaper came to him in the night, telling him that it was time, that he was going to have to pay the debt that he created that one evening. The reaper handed him the scythe and said that there was no world without death. He who kills death must become death himself.
And so that’s what Dean became.
He watched with tired eyes as his brother desperately tried to find a way to save Dean from this fate of an immortal eternity. He tried all the way up to the moment that Dean came for him one night, hand outstretched, saying that it was finally time to come with him.
And Sam did without question. He followed Death into the endless abyss, bowing his head for one final time.