Faith and Grace

Dean waved Cas over to a seat at the little table before grabbing a huge pitcher of water from the fridge and setting it down in front of the angel.

Yanking a cup out of the dish drainer, he tossed it to Castiel.

"Dean?"

The demon smirked. "Have a drink, Cas."

For all the eyes watching him were momentarily jet, the angel couldn't deny that it was still, somehow, Dean beneath the darkness. So he filled the cup and sipped slowly.

The water tasted pure, cool as it slipped down his throat, and it seemed to send a shivery tingle outward as he swallowed. While his fading Grace brought him physically ever closer to human, he had not previously felt true thirst. Now, it slowly consumed him, and he found himself draining one cup after the next, fighting down the urge to simply tilt the entire pitcher against his mouth and drain it till nothing remained. With each measure of liquid, he felt better, as if the broken levees within him that had been leaking Grace were now being patched and strengthened.

Pausing, he stared at Dean, not comprehending what was happening.

The demon who still called himself friend let loose a small snort of laughter. "It's holy water, doofus. The thing about holy water is that it ain't holy because of the ritual it's put through, it's the faith of whoever blesses and receives it. I figured that out a few weeks ago when I was looking into why it burns folks like me. Once a soul's been too twisted-" he blinked his eyes to black to show his meaning. "-there's no belief in hope left.

"You used to say I lacked faith, turns out so do you. It's not exactly Grace, I got no way of getting you any more of that that wouldn't piss you off when I killed some featherbrain. This is the closest I could get - water imbued with the human equivalent of your angel mojo. It won't fix you up, but it'll stop you running on empty or getting worse until we can work on a way to get you better."

Slowly wiping at his wet lips, Cas once again found himself wondering how such a soul could be so brilliant, conduct light and love despite now being utterly corrupted. Dean was impossible and astounding. And the angel could not regret the changes to himself since he had laid a hand on this soul all those years ago in Hell.

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a/n I'm on a bit of a SPN binge lately, and can't quite wrap my head around the newest episodes. So this is kinda using current canon, but mostly saying, screw it, what if Dean was just Dean with demony powers? Plus, I love the idea of Dean carting around this big old thing of holy water to his hotel, while he waited for Cas to answer his call, and Crowley's just sitting there fuming, all, "Deeeeeeean, what are you doing with that stuff? It burns like acid! You're myyyyy bestie, why won't you break up with your angel boyfriend already?"