Dean was having the most fun he'd had in a long time. Forcing his brother to molest a 16 year old girl was the end all, be all of human depravity. And it was turning him on as he continued to rub circles on her ass with his hard-on. And the smell of her fear and humiliation was so intoxicating that he almost forgot what he was doing.
"CHOP CHOP, SAMMY!", Dean called in a happy voice. "Times a wastin'!" Sam reached up again and gently laid his hand on the hair covering her mound. He let out a ragged breath as he stared at the floor. "Lower, Sam!", Dean said in his familiar sing-song voice. Y/N clamped her thighs shut and Dean shoved his feet in between hers and pried them apart. Sam's hand crept lower and he touched her folds with his fingertips. She was shaking badly and whimpering. Sam was sweating and panting, trying to hold himself together.
"PLEASE DEAN!", Sam wept and crumpled to the floor on all fours(Well, threes). "I can't do this to Y/N/N! She's just a kid!" Dean laughed with his chin on Y/N's shoulder, rubbing the flat of the blade over her stomach, smearing her blood in a circle.
"UP, UP, UP!", Dean called, waving the blade of his knife at the ceiling. "Get that hand back up there, Sam!" Sam shuddered as he sat up on his knees again. He looked up at Y/N and mouthed an 'I'm Sorry', begging her for forgiveness with his eyes. She nodded slightly and shut her eyes tightly. Sam touched her outer lips again and just held them there. "Move your finger back and forth, Sam", Dean grumbled irritably. Sam closed his eyes and slid his fingers back and forth along her folds. Y/N tried to distance herself from what was happening. She felt so terrible for Sam. She didn't blame him at all for what he was doing.
"Does it feel good, Y/N/N?, Dean whispered in her ear. He looked down at Sam and smiled. "Push your fingers in, Sammy. See if she's wet". Sam looked away with disgust. His hand started shaking and he started to feel like he was going to vomit. Just as he was about to do what Dean wanted , Y/N was jerked away from him and he fell forward. Sam looked up and saw that Cas had a hold of Dean's wrist that was holding the knife and his other arm around Dean's middle pinning his other arm against his body. Y/N fell to the the floor and crawled to the other side of the room.
"SAM! NOW!", Cas screamed. Sam pulled the syringe out of his back pocket and uncapped it with his teeth, spitting it out on the floor. Dean snarled at his brother like a rabid dog. Sam shoved the needle down into the space between Dean's neck and shoulder, grabbed the blade of the knife in Dean's hand, and sliced his own palm open on it. Sam slapped it over Dean's mouth as he began to scream.
"Exorcizamus te, omnis immundus spiritus. Hanc animam redintegra, lustra! Lustra!", Sam roared the incantation while Dean's scream was muffled in his hand. Dean jerked in Cas' grip and dropped the knife, every muscle in his body seizing up as Cas laid him on the floor. Dean's eyes bulged and he shrieked through clenched teeth. Sam had no idea what to expect and feared he might have done something wrong. Dean looked like he was dying. The veins all over his body began to bulge. Dean gasped and his body arched backward, his head and hips nearly touching. Sam thought that if that continued much longer, Dean's spine would snap.
"Can't you do something Cas?", Sam begged. "He's gonna break his back!" Cas got on top of Dean as he laid on his side on the floor. Cas straddled his hip and pulled Dean's shoulders into a more straightened posture. It took all the strength Cas had to hold Dean in that position. "What took you so long to get here, Cas?, Sam asked. "I almost..." Sam clapped his bloody hand over his mouth to keep from throwing up.
"I am sorry, Sam", Castiel said. "I had to wait until it was time to finish the ritual before I intervened. I didn't know how long I would be able to restrain him." Just as Cas thought Dean was calming, he started to shake violently and he let out the most gut wrenching wail that Sam had ever heard. Red light shot from his eyes and mouth and both Sam and Cas had to shield their eyes. Dean stopped screaming as the bright light cut out.
The room was dark for a few moments before Sam's eyes could adjust. Dean lay unconscious on the floor. Sam ran to his brother's side, kneeling on the floor next to his head. Cas placed a hand on Dean's chest and nodded at Sam. Sam let out a huge sigh of relief. Dean was alive. Cas grabbed Dean's right arm and held it up for Sam to see. The mark on his arm was gone.
"Cas, can you tell if he's gonna be OK?", Sam whispered. Cas touched Dean's head and nodded again. "Can you take him to his room? And stay with him, please". In an instant Cas and Dean were gone. Sam looked over at the far side of the room and saw Y/N huddled in the corner. She was hugging her knees and staring off into space. Sam walked about half way to her and then crouched down to make himself smaller and less intimidating. When he got close enough to her, he spoke.
"Y/N? Sweetie? Are you OK?", Sam whispered. He laid a warm hand on her shoulder. She flinched but Sam kept his hand on her. She was breathing heavy but didn't move away. She slowly turned her head and looked at Sam with wide eyes that were red and glistening with tears.
"Is it over?", she whispered. She was shaking like a leaf. Sam nodded and gave her a warm smile. She threw herself at him, squeezed him around his waist and cried tears of relief. Sam held her tight and let her release all her pent up emotion. She had been through so much and her ordeal never seemed to end. She had started to believe that she was destined to die at the hands of her best friend. When she realized their plan had worked, she didn't know how to feel. On one hand, she was alive. But on the other, she would now have to live with this trauma. And knowing that Dean and Sam would have to live with this as well made the guilt weigh on her.
So she just cried until she fell asleep.