This is based on a roleplay I did with a friend on instagram, so thank you, friend! Enjoy :)
“Dean, this isn't you. Please, remember who you were before.” Cas pleaded, his voice raspy and deep. A stray tear ran down his cheek as his hand fixed its grip on the angel blade it was holding.
Dean chuckled, his eyes a dark black. “I was nothing before. I'm finally alive now! And soon, you won't be.” He smiled, playing with the angel blade in his hand.
Cas didn't quite know what brought them to where they were now, blades aimed at one another, him cornered in the library of the bunker. Dean had gone off the rails since he became a demon, going after anything and everything that crossed his path, which was good for hunting, but not quite for when Sam and Cas tried to get him to at least act human again. Cas looked across from him at Sam's body lying lifeless on the floor. Dean didn't know what he was doing. He'd just killed his own brother, for heaven's sake!
“Dean, look what you've done already. You just killed your brother, the one you've been protecting your whole life.” Castiel tried to explain. He was surprised when he saw a tear running down Dean's face. He stood still, squinting and cocked his head slightly at the demon.
“What?” Dean asked, annoyed. That's when he felt the tear run down his cheek. He quickly swatted at it, shaking his head and laughing. “You think I still care – how sweet! Well, I have news for you, angel boy: I could care less what happens to him. He was only holding me back, anyway, always talking me out of just ending it all, keeping me alive as a worthless human. Well, now i'm free.” He smiled evilly.
Cas shook his head, his eyes still squinting. “You do still care. Deep inside, you're still human, and you don't like what you've done.” He thought of an idea. If Dean still had a human side, maybe he could get that part of him to show. Maybe he could stop all of this! It would be hard, but he could save Dean. He thought of Sam's trials, the last one being to cure a demon. All he needed was eight hours and purified human blood – that's it. He could keep Dean in the chamber they kept Crowley to keep him from going anywhere. He could do this.
Dean sighed, shaking his head. “You're one sad angel, aren't you, wasting your time here.” He laughed, but was taken off guard when the angel made his move, touching his two fingers to Dean's forehead. Then, he went limp, falling to the floor.
When Dean woke up, his hands were cuffed together with the demon-proofed handcuffs, the collar around his neck as well. He looked down, under the chair he was tied to was a devil's trap, at least ten feet in diameter. He looked around, finally finding the angel sitting on the table in the other side of the room.
“Hello, Dean,” Castiel greeted the newly awakened demon in the room with him.
Dean could see another person sitting in the room with them – a priest. He could tell the man was still alive, but asleep. He looked at Cas again. “What is this, huh?” He asked, trying to act tough. “You gonna keep me in here until I obey you? What kind of kinky shit is that?” He laughed a throaty laugh, throwing his head back. Castiel didn't react. He had been waiting for Dean to wake up to start the saving process.
He walked over to Dean, a syringe full of the human's blood in his hand. Once he reached Dean, he grabbed his head, tilting it to the side and jammed the needle in his neck, injecting the blood.
“Hey!” Dean growled angrily, wincing at the pinch of the needle in his neck. As Castiel pulled it away from him, his vision began to swim, the human blood flooding his demon system. He let out a blood-curdling scream.
Once that was over, he gasped for air, shaking his head before he began his deep chuckle. “Oh,” he nodded his head, “you're tying to cure me! What, get the idea from Sam's trials? Why not just kill me?” he spat at the angel, suddenly furious. He wanted Cas to think that the last thing he wanted to be was a human again.
About forty-five minutes after the first shot went by and Dean started to speak again. “You know,” He said, “Dean likes you. I mean he really likes you. He thinks about you all the time.”
Cas wasn't sure why Dean was talking in third-person. “Demons lie.” he said, almost reminding himself so he wouldn't believe him.
“But they also tell the truth.” Dean added with a smirk. When Cas wouldn't make eye contact, he gasped with realization. “You like him, too! I mean, I should have seen it before, the way you look at him, the way you carry yourself around him. He's a blind man, not seeing all those side-glances you give him.” he chuckled.
Four hours went by of blood injecting and Dean had given up on resisting. By the fifth injection, the human blood in him started to kick in, his human side coming out. “Come on, Cas, please!” he whined, squirming in his chair. “Just end it – I don't want to feel worthless again.” he looked up at Castiel who was still standing next to him from the last injection. “I finally feel important, I feel like I can do something when i'm a demon. I'm just sad and lonely as a human – please!”
Cas cocked his head, considering this, but just assumed it was the demon talking, trying to persuade him to kill Dean, so he shook it off, walking back to the human he was keeping captive and using for blood.
He filled up the syringe with the proper amount of blood and waited, watching Dean, who was still squirming and growling.
The last dose of blood was given, and Dean began chuckling loudly. “You really think he'll survive without me?” he threw his head back in laughter. “He's always wanted this. He'll never forgive you. Being a demon is what keeps him sane, what makes him happy – what makes me happy. I am Dean Winchester, and I am one hell of a demon.” Dean spat Castiel's way, his eyes flooding black.
Cas scowled at the demon in front of him. He spread the human blood over his palm and grabbed Dean's hair, quietly starting the exorcism. “Exorcizamus te,” This made Dean squirm uncomfortably, beginning to scream again. Cas muttered the last word and wasted no time, slamming his hand onto Dean's mouth, a bright light shone through Dean's eyes before he went limp.
Cas took his hand away. “Dean,” he lifted the new man's head up to look at him.
Dean blinked at Cas, squirming in his chains. “Cas?” he breathed lightly. Castiel smiled, unlocking every chain Dean had on him with a wave of his hand. He helped the Winchester stand up, but he was still too weak to walk on his own, resulting in him falling to the floor.
Cas bent down beside him, lifting his chin up once again. “Thank you,” Dean said quietly, closing his eyes.
Cas rested his forehead on Dean's, closing his eyes as well. He sent out a message to all angels. “Dean Winchester is saved.”
