Castiel made sure to keep his distance from the Winchesters but still watched over them from Heaven. The angels were right; emotions were the doorway to doubt, because Cas was sure if there was anywhere in this universe he was Created to be, it was by Dean's side. Doubt sowed its first seed in Cas' brain, and he felt the pull of rebellion, for a better cause. For Dean.

Dean was 23 when Sam left him and John for Stanford. Dean prayed to Castiel that night, from the safety of the Impala while John got drunk in a local bar.

Cas, Sam's gone. I don't know if you're watching, but he left for college. I don't know if you have your angel ears on, or whether or not you know what's happening down here right now, but I could really do with seeing you. I know you can't, and that's fine, but know that I miss you.

Castiel missed Dean too, so much. He'd give anything to see the Winchester one more time, to wrap his arms around the man's frame in a gesture of comfort and care. But he can't, because if he does, Michael will make them both forget everything they've been through. And Castiel does not want to forget.

Dean begins hunting alone, and John goes off on hunts without him. They always reconvene, but Dean sees more at ease seeing less of his father. He's a more than capable hunter, but that doesn't stop Castiel from sometimes worrying and fighting the urge to fly down to Heaven when it looks like the odds are stacked against Dean too high to be knocked down. But Dean always makes it through, always fires a quick prayer to Cas at the end of a really tiring hunt, and even though the whole of the garrison can hear it, Castiel doesn't worry too much, because he hasn't interfered with Dean, not even gone down to Earth physically since their last goodbye.

Castiel follows his orders to the mark, because, in the end, he is a good soldier. He doesn't tread the line that separates him from Dean, because he knows that when he does, it's game over. And there's nothing he wants more than to be able to keep his memories of Dean. Castiel has watched the Winchester grow from a boy to a man, and somewhere along the way he fell in love, and as painful as it was, he doesn't regret it, no matter what he may say or how he may act.

He feels alone; Gabriel has left him, he can no longer talk to his best friend, and none of the other angels would understand what he was experiencing. Angels are unfeeling, of course. Castiel was the exception. But then, Castiel had always been an exception. Since the start, he had been more feeling, more merciful than his brothers. More human. He empathises with humanity, a trait not shared by other angels, and one that alienates him.

Castiel misses Dean.