Maybe if he had payed attention he would have realized it earlier. Before everything had gone wrong. Before Gabriel died. For them no less.
It was only after Gabriel's death that Sam realized what he was going through. To have to watch your family kill each other, and not be able to stop it. And then to be alone, for centuries. Eons of hiding who you were. Gabe must have felt so utterly alone. It was only after, that Sam realized how much he liked the trickster.
But now he was dead, and there was nothing Sam could do to fix it. Leaning forward into his hands, Sam sent one last prayer to the archangel.
"Gabe? Gabriel, if you're there... If there's anyway you're still alive..."
Sam stopped, he was being an idiot. Of course he wasn't still alive, Sam had seen the trickster's wings burnt into the ground himself!
But, shakily Sam went on. "If you're not dead, please.... we need you. I need you."
And with that Sam stopped. Letting out a weary sigh, he sat up and got ready for bed, only to lie there for hours in the dark thinking of everything and nothing, but mostly of a certain archangel that left a tear in his heart.
Hundreds of miles away, sitting on a rock ledge overlooking the ocean, Gabriel received a prayer. Shocked that Sam of all people would pray to him especially when he was supposed to be dead. Because that's just it, he was supposed to be dead. The archangel had been ready to give his life to protect those two humans, although if he was honest with himself one in particular, and by some fluke or miracle, here he was. Alive. He had felt the blade enter his chest, felt his grace flood out of him. So, why wasn't he dead?
Giving up on figuring out how he was alive, Gabriel turned his thoughts to the prayer he received. Should he go back to team free will? Or was it better to go into hiding again?
Standing up, the archangel made his decision, and with a flutter of wings the cliff was empty again.