Dean's lying in a hospital bed, monitors beeping and glowing in the calming gloom. Sam sits in a chair beside his bed, hair threaded slightly with grey, Castiel remembers him as younger.

It's been so long.

He always feared, yes, feared – that one day he would hear Dean call and he would not go right away. He would have to wait, there would be some task to take his focus.

And that it would be years on earth, before he got there.

Too late.

Always too late. Too late to the gates of hell, to tell Dean the truth about the angels, about Lilith. He was too late with his declarations, with his loyalties. Too late in his search for God. Too late to make any kind of difference.

"Do something." Sam growls, voice dry. He hasn't been eating, drinking or sleeping – Dean needs him.

Castiel envies that devotion. He has no need of food, sleep or water. Yet he is still not here for Dean when it counts. He is responsible for heaven, for all the angels, for hell and for earth. He made himself a God once, but that power is long since gone, flown. Now he has an empire of thieves and rogues.

"I can't."

"Bullshit." Sam spits. "You can save him. You just won't."

"Yes."

"How can you? When it's your fault he's back, that he lived all this time, through the apocalypse, through..."

"I know." Castiel sighs, because he's tired. "But...it's not for me to determine..."

"You used to think it was." Sam is relentless.

"I've grown up." Castiel grits out. Because of course that's what it was. He has the perspective of an ancient child – Dean fought everything he could find, Sam ran away to college, rebellion is what makes children become adults. It's only human.

And Castiel was once human.

"Please...save him." Sam begs, looking down at the unconscious form of his brother, also greying at the temples, laid low by a blood clot and hanging between life and a death Dean is already acquainted with.

"Sam..."

"No. Just...get out. Go!" Sam yells. "You're...you have no idea what it is to love someone, to need someone like I need him. So. Get. Out."

"Sam...he's gone."

The monitors drone in the stillness.

Castiel glances up, and he's done this before, looking to the heavens for God, for guidance, for relief from the terrible pressure of his own nature versus Dean's expectations.

Now he senses a new arrival, and he feels a spike of what he identifies as joy.

Dean, in the house of the lord.

Though of course, it is his house now.

"Tell him I love him." Sam says numbly.

"You'll see him, it's not like it was there..."

"Just get out of here." Sam pleads, eyes on his brother's corpse.

Castiel leaves like a dying breath.

In heaven, Dean stands beside himself in a dark barn, listening to something that is not the wind rattling over the roof and stirring up the dust. The doors at the end of the building sway open, the bar over them withdrawing, the symbols painted on the walls illuminated in the harsh bursts of exploding bulbs as a creature that is not of earth wanders into the midst of his ruined world, clothed in borrowed flesh.

"How did we get here?" he asks, watching his other self watch the angel before him.

"The scenic route." The Castiel who is only slightly older than the other, but infinitely wiser says from behind him.

"Long drive." Dean comments. "Do you remember, what it felt like to be him?"

"Less and less...though sometimes...his innocence irritates me." Castiel sounds sad, old. "Sometimes I envy him. He has your awe, your attention to look forward to."

"But he's not here yet." Dean points out. "He doesn't get what it is you have, not yet."

Dean turns, and, for the first time since he entered the hospital, he smiles. He touches Castiel hesitantly, drawing the former angel, the former God and now the oddity, the in-between creature, into a kiss.

Their lips touch and Dean drinks in Castiel's relieved sigh like a balm for his cracked soul.

Behind them, Dean slams a knife into Castiel's chest.

They have so much to learn.