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The first dose was shoved down his throat rather unceremoniously. He had just tried to kill his own brother with a hammer, so he thought that was, y’know, fair. In the grand scheme of it all, or whatever.
When Dean had woken up dead, he’d immediately known he was different. Not just physically but wholly. Every last cell of him, every thread of his soul and fibre of his being, had been transformed, forged in fire and flame, strengthened with a resolve he thought he’d lost in his youth.
A Knight of Hell, they called him.
Some knight he was now, in chains in his own basement. Locked up in the aimless corridors of the bunker like some captive minotaur, a monster kept from fulfilling his role.
Everything was corrupted, had been, really, ever since he picked up that blade. He’d never expected his angel’s grace to join the ranks of the things he’d have to ruin, but here he was. Castiel’s grace had slid down his throat like ichor, despite his fighting, and despite his filth.
When Castiel had healed him in the past, it was from the outside in. His hands would come to rest on Dean’s injured flesh, his grace would pulse through them like electricity, and the connection would stop when Cas pulled away. But this - this was more refined. This wasn’t Castiel’s touch; this was Castiel. This was Castiel, healing him from the inside out.
When it was time for the second dose, Dean heard his captors as they paused in front of the door. Their footsteps stopped abruptly, like both Sam and Cas remembered who was waiting for them on the other side. What was waiting for them. After they braced themselves and opened the door, Dean felt an incredible rage bubbling inside him.
Dean fought just as hard against them this time as the first, thrashing about and gnashing his teeth and flitting his newly minted true-form about the devil’s trap bubble he was imprisoned within.
This second portion only strengthened the hold that the grace was gaining on his consciousness. He could feel it weaving through his insides, could sense the way it tugged at his humanity, stretching and kneading the remnants of life and soul into something more concrete.
Something must have changed because when it was time for the third dose, Cas came alone. Dean heard both sets of steps as far as the hallway, but only his angel approached, the vial of grace clutched between his fingers.
“Aw, am I human enough now that you can face me alone?” Dean’s voice came out sickly sweet, the kind of artificial sugar that came hand in hand with his lack of mortality. “Didja pretty-up my demon face? Spread some angel-gloss on my nine mouths?”
Dean puffed out his chest, as much a picture of confidence as could be managed while chained to a chair.
“Can you even see me? The real me?” Dean wasn’t sure what about his words did it, but Castiel flinched at that. When he looked back to Dean, his eyes flickered over the space around Dean first.
Cas took a deep breath before answering. “You mean if I can see the demon’s true face?”
“I’m the demon, Cas. That’s me.”
Castiel looked away again. “I can, yes. See you.”
“Well, then, how come I can’t see you? Doesn’t seem fair, does it? Makes a guy feel a li'l exposed.” Dean took stock of how he was sitting; legs spread wide, feet braced far apart, shoulders back, head lolled to the side. Dean knew how he looked. He poked his tongue out, pink and wet, and watched as Cas followed the movement with his eyes.
“You can’t see me?” Was that… Relief?
Dean shook his head no, and for fun, flitted through a few of his demonic faces, flashing his body’s eyes black for pure dramatics. The display seemed to make Cas uneasy, and something about the way he got shifty was enjoyable for Dean. It was reminiscent of the little cat-and-mouse games he would play with his and Crowley’s targets.
This was just a little last hoorah, a little bit of fun before it was all over. It didn’t have to be more than that.
Cas wasn’t paying attention anymore; he was circling Dean like he was prey, or more aptly - like Dean was a puzzle, something to be taken apart and put back together, solved and fixed, like he could pick out the wrong pieces and leave them out, burn them to ash and ignore the holes in the final picture.
“Could you see me before we started the treatment?”
“The treatment?” Dean laughed, the sound cruel and echoing. “That what we’re calling it? And how the fuck would I know? You didn’t exactly introduce yourself before you grabbed me from behind and threw me into a fuckin' devil’s trap. These things don’t feel great, y’know. They hurt, honestly.”
Castiel straightened up, squinting at Dean, squinting at the swirling forms around him. “Hm.”
Dean would love to have his hands free now, would love the chance to knock some fucking sense into his angel, feel the way the soft skin of his cheek yields to Dean’s hardened fist. Pay him back for the way his grace was constricting around the darkness that filled his chest, really make him see what Dean had become before he’s torn back out from the depths of it.
Dean’s eyes were drawn to Castiel’s grace again, the little glass vial that glowed with the essence of him. Dean wanted it as much as he didn’t. He’d be lying if he said the turmoil it was creating within him wasn’t compelling, wasn’t more interesting than chasing empty highs in the form of false-righteous kills. Grace was tangling with whatever smoke his soul had morphed into, and it felt as hellish as it did heavenly.
Cas stepped forward, his feet centimeters from the circumference of the prison he’d trapped Dean inside.
Toeing the line as always. That was his angel.
His. Dean was only allowed to have when he was a demon. Possession came with the territory, he guessed. As soon as he was cured, Castiel would return to the way he was, as unattainable and celestial as ever.
“Are you weakened by the trap? Is that why you can’t see me?”
Dean sighed, long-suffering and exaggerated. “Cas, c’mon man, how the fuck would I know. I’ve never been in one of these things. Haven’t run into an angel either. Guess they’ve been staying clear. Knight of Hell, and all.”
Cas stepped over the line, the vial of grace gleaming blue against the grime of the dungeon.
Dean didn’t fight while Cas fed him his grace. He was too busy searching for a glimpse of Castiel in the air around them.
Cas walked out without another word, leaving tendrils of his grace to take deeper root in Dean’s soul.
The pain was exquisite. Dean writhed and screamed and cried, the sound coming from deep within him and deeper within his true-form. He wailed from his nine mouths, he scratched with claws and nails and talons. He pounded on the barrier of the devil’s trap.
Dean knew the fight was useless, but when had that ever stopped him?
The pain distracted Dean from the sound of his captors’ fourth approach. Cas was halfway across the floor towards him before Dean noticed.
Castiel flinched when Dean looked up, decay-black meeting grace-blue. Dean tried to flash a few faces, snarl and howl and show his teeth, but the threads of grace were stronger than he had thought. He was tethered in place, the last semblance of control ripped from him.
In the silence stood the two creatures, both equally marred with humanity.
At least Dean saw it as the problem that it was. Castiel was in denial, saw his humanity as a strength. Dean knew better.
The demon fought hard and loud enough that Sam opened the door into the hallway, looking in with wide eyes. Dean only noticed when Cas turned and ordered him out, the flash of heaven’s wrath barely contained behind his vessel’s eyes.
There was no avoiding the invasion. With Castiel’s fingers hooked around Dean’s jaw, forcing his mouth open, the grace slides right in. Like it was meant to be there; like it had a home inside Dean.
Cas barely looked at him on the way out.
That time, the burn was less intense. If Dean closed his eyes and focused, he could picture the grace scraping the inside of his body, digging out his darkest and deepest parts and purifying them. It was a healing like no other, but it was just as much a destruction.
An hour later, Castiel came alone, the door left swinging on its hinges as if to show off this fact.
“Just you? No chaperone this time?” Dean spread his legs, stretching against the restraints at his ankles. He let his thighs fall apart, leaned back against the chair, felt his shirt ride up a bit at his hips. “Aren’t ya scared of the big bad wolf?”
Cas barely acknowledged him, opting instead to pull a chair out and take a seat. “Why would I be? You’re more human than demon now.”
Dean watched as the angel took out a small blade - watched as he took out an empty vial.
Dean watched as Castiel dragged the sharpened edge against his own flesh and drained his own essence into a vial for Dean to consume. Always ready to sacrifice, always happy to bleed.
The sight was mesmerizing, skin parted to allow a stream of light to escape, blood from the vessel’s veins tinging the whole scene a delicious red. Dean wanted to drink straight from the source.
Once Castiel was finished, he healed himself with a thought, flesh knitting together seamlessly, candy red blood evaporated into the air. What a waste.
Dean pouted.
When Castiel stepped forward, sixth dose in hand, Dean locked eyes with him. He knew the demon-black was faded now, and the effect was gone with it, but he still had a few tricks up his sleeve.
Dean let his eyelashes flutter shut, his mouth parting as he let his tongue loll out onto his bottom lip. He knew what he looked like.
Cas reached out to rest his hand on the back of Dean’s neck, a precaution in case the demon reared its heads and put up a fight. Instead, Dean leaned into the touch and opened his eyes to meet Castiel’s once again.
The wide-eyed look he was met with was more than reward enough. When Castiel tipped the vial, Dean breathed in.
Communion.
“Do all angels taste this good, or just mine?” Dean watched Castiel’s jaw clench. Whether it was at the words or the display Dean had put on - he couldn’t be sure.
Dean wasn’t lying, though. On this side of the halfway point, the pain was gone, leaving behind only Castiel. His grace was more him than Dean had ever been able to see, and now it was inside him. Now it was part of him. Now Castiel was branded on his shoulder, etched on his ribs, stitched through the very fibers of him.
And, sure, maybe taste wasn’t the right sense to be focused on, but again. Dean knew how he sounded. He knew how he looked.
And so did Castiel, based on the hitch of breath the question triggered.
Dean never got his answer; Castiel only left him alone. Dean pretended he didn’t feel the ghost of abandonment settle into his chest. Feelings that he hadn’t had use for as a demon were flooding back with each dose.
Castiel returned shortly before the hour was up and sat back in the chair just outside Dean’s devil’s trap. When he pulled out the knife again, vial close behind, Dean shook his head.
“C’mon, let’s skip that step, huh? Save the extra dish?”
Castiel’s head shot up, eyes squinted in question.
“Don’t make me beg, Cas. We’re already here, right? So I might as well lay down and take it. Alright, I’ll do it. I’ll bend over and arch my back real pretty for ya. I just want to taste.” The demon must still be hanging on tight if Dean had the words to ask for what he wanted. Despite the shock he felt at his own words, Dean only flashed a smirk.
Castiel’s confusion didn’t seem to clear. Dean bowed his head best he could, pulling his shoulders in tight. “No vial. Just. Come here, will you?” Dean hadn’t missed shame these last few weeks.
Dean didn’t dare look up, but slowly, Castiel stepped into sight, stopping once he’d reached the sigil line.
A beat.
And then a second.
Dean raised his eyes in time to watch Castiel flick the blade across his wrist. He dropped the knife, the clattering sound doing nothing to break the tension in the room.
Dean watched as Castiel took an unnecessary breath and crossed the line. Like a habit, Castiel’s uninjured hand came to rest on the bolt of Dean’s jaw, Castiel’s feet planted firmly behind Dean’s prison-chair. Dean could only see him if he craned his neck back and instead chose to press into Castiel’s hold, leaning his face into the impossibly soft touch he found there.
Dean let Castiel turn his head slightly and licked his lips as the cut moved into view. He wanted nothing more but to latch on, grab with both his hands and gorge himself until he’d had his fill, until Castiel was nothing but swirling essence inside him, grace and light and holiness and purity, until Dean could find a way to snub that out too.
Instead, he waited; waited as Castiel positioned his wrist in front of Dean’s lips, waited as Castiel’s blood dripped red and rusted down onto Dean’s chest, down over his stomach, down onto his lap. The grace waited at the surface, pooling in impossible little puddles of light on Cas’s skin.
It was close enough that Dean just needed to stick his tongue out for a taste. It was close enough that Dean could take and take and take and take.
It was close enough that waiting was a reward in itself.
Castiel closed the gap and pushed with one hand to connect Dean’s lips with the source of grace. Dean moaned at the contact, took a greedy inhale, parted his lips, pressed out his tongue, and drank. The blood was a familiar flavor, but the way it mixed with grace was anything but.
The taste was sunshine. It was bright white light and it was patience and it was purity and it was God, not g-o-d god, not fathergod, but God, something Dean hadn’t experienced before, not until now, not until he knew Castiel inside and out and Castiel knew him in return.
When Cas pulled back, Dean whined, low and thick in the back of his throat. He felt the blood coating his lips, felt the grace settling low in his belly. His eyes were hooded, lids heavy with his drink.
“I’ve never told you how goddamned good you feel. I’ve always thought it… but now that I can taste you? God, Cas.”
Cas was standing behind him, face obscured, body language entirely hidden. Dean tried again, leaning into it, letting himself feel drunk on Castiel’s grace.
“Really, sweetheart. You taste so fucking good. You were addicting enough before, but this is next level.”
Cas spoke up. “Before? You… You can’t….”
Regret twisted dark in Dean’s stomach, blotting out the light. “Yeah, you’re right. A monster like me, angel like you? Is human any better?”
Castiel took careful steps around him, staying within the circle as he moved to look Dean in the eye. “You’re not a monster.”
“Who are you reassuring?” Dean spit the words back, and Castiel blinked twice and left the room.
One more carefully orchestrated dance later, the ritual would be complete. Once more, Castiel would enter the room, once more, Dean would press his lips to Castiel’s skin. Once more, he would drink.
When he finished, Dean reveled in the effects, eyes sliding shut as he floated inside his mind, as the last strands of hell were drowned out with holy light. Knight of Hell gave way to daylight.
He barely noticed as Castiel untied his wrists and ankles, he barely noticed when Castiel dragged his blade through the barrier of the devil trap. He barely noticed as Castiel turned his back and left him there to sit in his own drunken shame.
Human once more.