Setting: Dean is dragged to Hell by one of Lilith's hell hounds. Sam, distraught, prays every day that he can somehow get his brother back somehow, but despite his efforts, no demon will take a deal for him to trade places with his brother. He exhausts every option beyond belief, spiraling into self-destructive habits, until one day hope arrives: an Angel of the Lord. Castiel is beginning to lose interest in his orders, and after watching over Dean, begins to fall in love with him. He reveals his identity and existence to Sam, and together they break into Hell in order to retrieve Dean.
(I'm new to this so please tell me honestly what you think, if anyone likes it i'll follow the storyline and add in a 'Then' timeline of when Sam first meets Cas as well)
Now
The stench of death unfolded itself from the open door, slowly reaching out to them. The smell was horrific; Castiel hunched over in the corner gagging, and Sam was trying his best not to empty his stomach of the cheap motel food they had managed buy with money hustled from pool. Even as an angel, the reek was unbearable. Castiel stepped forward, ready with his angel blade, and led them into the darkness. A figure loomed before them and Castiel sprang into action heading for the threat, but Sam ripped his arm back and pushed Castiel behind him.
"Cas, stop, stop! It's him."
Now in the room, the smell of rotting flesh was unbearable. Castiel was holding his breath, yet he still somehow managed a choke when he saw Dean in front of him, after months and months cut off from him he was finally here, next to the one he loved. Dean was hanging by his wrists, feet swaying above the floor from the breeze they had bought with them through the open door.
"Look what they've done to you Dean," Castiel's voice broke, "look what they've done".
The walls and floor around her were painted in reds and browns from years of blood and torture. Chunks of Dean's flesh were missing or peeling away, the bones in his wrists were visible around the manacles. Maggots swarmed in and out of the decaying flesh in one leg, and there was no part of him which was clean of slashes or lacerations and several brands were burned into the remaining skin. Barbed iron rods had been completely pushed through Dean's body and were peering out of his back, as if to dare anyone to attempt to remove them without carving his insides further. Sam, hunter's instinct kicking in, was the first to notice the walls around them; in each spot hung blades, hooks, hammers, and the worst torture devices imaginable.
When Castiel stood still frozen from the horror of the friend they were facing, Sam cleared his head, swallowed his emotions, and tried to pretend he didn't know his brother, that this was just another rescue mission and nothing more. He hated to, but he knew from memories that Dean was his weakness; if he wanted his brother safe, he had to act like any hunter would saving a victim on a hunt.
"We need to go," Sam said, quickly formulating plans. "We need to get out now, before the demons realise our distraction. Guard the door Cas, make sure the demons haven't been alerted."
Castiel didn't hear the orders from his recently found adoptive brother. He was focused on Deans' beaten face, stroking his shoulder as lightly as he could with his hand in fear of damaging him more.
"Cas." Sam's voice echoed somewhere in the back of his mind. The palm of a hand made contact with the side of Castiels's head and he slumped over in shock, one hand grasping at his angel blade to fend off the attacker, the other reaching to the stinging handprint on his face.
"Cas! I know it's hard to see him like this, god knows I understand how you feel, but I need you here! Focused! If you want to get Dean out of here, if you want to see him smiling again then you need to listen to me and do as I say."
Castiel closed his eyes, wanting to sit at Dean's feet and waste away with him, but anger began to well up inside him. He jabbed at his eyes with his bruised hand, annoyed and ashamed with himself for breaking down instead of helping Sam, instead of doing his duty and following orders. Instinct found its way to the surface, and he pushed himself up from the blood soaked dirt and headed for the hallway he was told to guard. It was the first time in a long while he had taken orders from anyone except Anna, one of the angels which governed over him, but he knew Sam was the best hunter in the States, well, second best after Dean. I was wrong, he thought. I told myself I could protect him, yet here the Sam is, helping to clean up the mess I've made. He turned to see Sam take his brother in his arms gently, as if he were paper that could tear with even the smallest of movements. This is my fault, all of it. If I'd stopped myself, if I hadn't fallen for him then maybe my brother would have allowed me to stop the hellhounds from dragging him down here in the first place instead of teaching me a lesson. The angels needed Dean. He knew that, his siblings knew that, but it didn't prevent Michael from punishing Cas for beginning to feel for him. And letting him see Dean suffer was a lesson to remember.
Sam pulled his brothers wrists free from the manacles, and inspected the damage.
"How long has he been here? There's no way this is from four months of torture, it looks like he's been here for-"
"Years," Castiel said. "He's been gone from you for four months. Down here, time is…different. A month feels closer to something like ten years. Alistair has had him, has been torturing him, carving him, for four decades."
