Author's Note: I posted a prologue to this a few days ago, and I decided to ditch it, but this is the fic I was talking about!

"If you don't wake up, I swear I'm gonna tip yesterday's toilet water onto you," a rowdy voice yelled, and Castiel awoke, suddenly. He looked up, gingerly, and saw Sam standing above him, looking annoyed. Castiel rubbed his eyes, but the figure above him didn't falter.
He must have been hallucinating. Perhaps he had developed a psychological condition, because of what had happened. Sam was dead. He had died seven years ago, and Castiel visited him in Heaven.
He must have been in Heaven as well. That was the only reasonable answer. If Sam was alive (which is definitely not possible) then he wouldn't be here. Especially threatening to pour water over Castiel. It's not like Sam had never said anything like that to Dean, but right after he'd been resurrected? It just didn't make sense.
Was Dean around here too? He looked up, and saw nothing but old rugs and sleeping bags cluttered in the small room. He and Sam were the only ones around.
Whose Heaven was this? It wasn't one he'd visited before. It couldn't have been Dean's, because Dean had always moaned about uncomfortable motel beds. So was it Sam's? Or his?
"How did I die?" he asked Sam, as he reached out to touch Sam, to see if he was real. Sam jerked back, "Woah, man, are you okay?" Castiel nodded, "I think so. How did I die?" Castiel repeated, which made Sam look even more confused. "You're not dead. Are you sure you're okay?"
"Why wouldn't I be?"
"You were meant to be on patrol, but we couldn't wake you up."
"Are you sure I'm not in Heaven?"
"Yes. What's up with you? Are you really okay?"
"Yes, Sam," Castiel sighed. He tilted his head, "Where's Dean?"
"Dean?" Sam asked suspiciously, "How do you know Dean?"
"I saved him from Hell," Castiel said, unblinking.
Sam shook his head, "No that was Uriel. How did you know about that?" Castiel narrowed his eyes, "Something isn't right, Sam. I don't remember arriving here. I just remember-" he froze, and Sam stares even more.

"Castiel," Death acknowledges, as he appears in front of Castiel, "I'm here for Dean."
"Why? Where are the reapers?" Castiel asks, through tear-stained eyes. Death smiles, the emotion strange on his face, "Despite being the nuisance he is, I am rather fond of Dean. I thought I'd take the time to escort him beyond the Veil myself."
"What will happen to him?"
"Despite being a human for ten years, Castiel, I am sure you haven't forgotten the rules we have to follow. I can't tell you."
Castiel hears a voice in the distance. It sounds vaguely like Dean, and he tries to listen to it, but he can't make out any words. Death stares into the corner of the warehouse, and Castiel's eyes follow Death's, as he eagerly says, "Dean? Is Dean there?"
"Yes," Death sighs, clicking his fingers. Dean suddenly appears, and Castiel breathes a sigh of relief. He attempts to hold his hand, but there is nothing to grasp; Castiel's hand goes straight through Dean's. "Cas," Dean says softly, and it nearly breaks his heart. "I'm sorry," Castiel replies, through his tears. Dean shakes his head, "Don't be. Just be- just be strong, okay? Remember that I love you, and don't forget to look after my Baby," Dean says, as a tear begins to roll down his cheek. Castiel wants to hold him; to kiss him one last time, but he knows he can't, and it breaks his heart. "Dean, you died because of me. I will do whatever I can to get you back," he promises, and Dean smiles. Death interrupts, "However touching this is, Dean and I have somewhere to be. If you please, say your goodbyes now," he pulled out an old fob watch, "I have other appointments."
Castiel nods, "Yes, of course. Dean, I am sorry."
"You don't need to be, Cas. Just have a good life, and it'll be fine."
"I love you."
"I know."
"Was that a Star Wars reference?"
"Finally, a reference you get!"
Death tapped his watch, and Castiel apologised, "Sorry. Goodbye Dean," The words were what broken him; he knew Dean was gone, and he decided then that he'd do anything in his power to get him back. When Dean finally said goodbye, and he and Death disappeared, Castiel began walking to the nearest crossroad.

Castiel returned back to consciousness with a gasp. A million questions filled his head? Had he sold his soul? What was the price? How many years did I have left?
He knew Dean would hate him for doing this, but if he had, then Dean was alive, and that was what mattered.
Was that why Sam was alive? Had he sold his soul for both of them? What kind of crossroad demon would accept that deal?
"Dean," he whispered, and Sam shook him, waking him up further. There was a woman beside him, who looked over him, cautiously. "How are you feeling?" the woman asked.
"I need to find Dean," Castiel said, sitting up. The woman frowned, and Sam admitted, "Dean's not here. I haven't seen him in years."
"Years?" Castiel asked, his voice nervously squeaking. If he had sold his soul, why had Dean and Sam not spoken for that long? Something was definitely wrong.
"Yeah, since I, uh, since Lucifer came out of the Cage," Sam hesitated, looking down, "We had a big argument."
"I am aware of that."
"How do you know that? Only three people-" realisation spread across Sam's face, "Are you Ruby?"
"No, Sam. I'm Castiel. I saved Dean from Hell."
"You're fucking Ruby, aren't you? Get out of Emanuel, you demonic bitch!" Sam grabbed the holy water, and sprayed it at Castiel. Castiel stated, "I am not Ruby. Who is Emanuel?"
"You're Emanuel," Sam said, confused. Castiel tilted his head, "I am Castiel."
"That's your name?" the woman cut in, "Do you remember anything else, 'Castiel'?"
"I saved Dean from Hell. We stopped the apocalypse together," Castiel said. This wasn't supposed to happen. What price had he paid when he sold his soul? Who would accept such a price?
Sam's eyebrows rose in interest, "How did you stop the apocalypse?"
"I'd rather not discuss that," Castiel said. It was still a touchy subject; after all, Sam had died. He and Dean had rarely mentioned it. "I'd rather just find Dean."
"Sam, I'd like a word," the nurse interrupted, and Sam nodded. They walked out of the room, and left with a nervous-looking man standing in the corner. "Chuck?" Castiel asked, and the man jumped, and then gawked at Castiel, "What's it to you?"
"Have you been having any prophecies lately?" Castiel inquired. Chuck shifted uncomfortably, "No, I-I think the angels cut me off."
"What was the last one you had?"
"Sam free- Lucifer being released from his cage," he corrected himself. Castiel nodded, "Where's Dean?"
"The angels have him. There's a rumour that he's Michael vessel."
"And you're not trying to stop him saying yes?"
"We've looked everywhere we could. He's probably already said yes. Torture is pretty bad upstairs."
"I know," Castiel said, thinking back to the separation from his vessel in the weeks before Lucifer was released. Chuck tilted his head slightly, "You think you're Castiel?"
"I am Castiel."
"The angels talk about you sometimes. I mean, I don't just get the Winchester channel all the time; sometimes I get Angel radio too. Uh, do you know Uriel? You were friends or something?" Chuck blabbed, and Castiel remembered when Anna had saved his life by killing Uriel, "Yes. We were friends."
"He thinks about you sometimes," Chuck admitted, "They all do. But you're dead."
"I'm not sure how, but I will find out," Castiel said, as Sam and the woman entered the room again. "Castiel," the woman smiled, "I am Dr Lee. Sam and Dean stopped me from the Croatoan virus in 2006. I need you to answer my questions, okay?"
"Okay."
"You said you rescued Dean from Hell. Do you remember why?"
"It was my orders from heaven; rescue the righteous man." Sam glanced worryingly at the doctor, and the doctor just nodded.
"Your orders from Heaven?" Dr Lee questioned. Castiel laughed lightly, and looked down, "Yes. I am- I was an angel. I fell, after Lucifer was released, for Dean."
"Wait, for Dean?" Sam interrupted. Castiel quickly corrected himself, "And for you, of course. It was a price I paid for stopping the apocalypse."
"How exactly did you stop the apocalypse?" Sam asked, earning a glare from Dr Lee. "I told you, I don't want to talk about it," Castiel snapped, "We need to find Dean, now." He didn't want to tell Sam that he was really dead, if he didn't know. He didn't know where Dean was, or if Dean was safe, and it was still the apocalypse. Was this the price he had paid for Dean's life?
"That's okay," the doctor said, comfortingly. There was brief silence, before Sam suggested, "There's rumours that there's a group of survivors nearby; wanna go check it out?"
"Yes," Castiel said immediately, knowing it would be good to check out the rest of the world. Dean had told him about his trip to 2014, and he wondered whether the world he was in was similar. Judging the similarities, it probably was.
Sam walked him out of the barn they were in, where there were several care parked on the dirt track outside the barn. Sam walked over to one of them, an old Land Rover, and gets in the back seat. Castiel joined him, aware that the last car he'd stepped into was the Impala. Sam noticed the sad look on his face, and reasoned, "I know it's not exactly the Impala, but it gets us around in this hellhole." He gestured at the man sitting in the driving seat, "We're all set, Jim," and then engine started. Castiel watched as the driver, Jim, drove out of the dirt track, and compared his driving to Dean's.
Jim didn't drive a car like Dean had. Dean's touches had been soft; doing everything he could to not give his Baby a single dent. Jim didn't care about the car he was driving; it already had many scratches, and was beaten by age, unlike the Impala, which Dean had attempted to make good as new every time it was destroyed.
"So, what happened after you stopped the apocalypse?" Sam asked, casually. Castiel blinked, startled out of his thought, "What?"
"Y'know, in the world you were in. What happened after the heroes saved the day?"
"We stopped hunting," Castiel faltered, considering telling Sam the truth, but he lied anyway, "We got normal lives."
"Well, sounds like a better reality that this one. Dean's okay, in it?"
"He's-" he paused, knowing that if he told Sam, then maybe he'd help him more, and- he couldn't know. Sam couldn't know. "He's fine."
"Sounds a lot better than this," Sam shrugged, as the car turned onto another road, into a deserted village. "It's not," Castiel said, sadly. Sam raised his eyebrows, "Why not? Anywhere's better than this."
"It was missing a few things."
"Like good old spontaneous combustion?"
"Sorry?"
"Here, in this world, a bunch of people just caught fire suddenly, all over the world. It started the apocalypse, caused lots of chaos. I never actually saw any of it, but I heard. There was fish raining from the sky, giant floods, and just about every other apocalyptic sign you could think of. We're probably the only survivors."
"Why didn't you see?" Castiel asked. That part of the apocalypse never happened.
Sam tapped his sunglasses, which he'd been wearing since Castiel had seen him. He took them off, revealing two glass eyes, "I saw Lucifer," he said simply. Castiel murmured, "I'm sorry."
"Don't be. It was my fault; I should never have trusted Ruby. Dean was right," Sam said, gloomily. Castiel awkwardly looked around, unsure how to comfort Sam. "We were all happy, in the world I come from."
"That's nice," Sam says before asking, "How do you think you got here?"
"I'm not sure. I think I sold my soul," Castiel admits, he thinks hard, and the memory comes gushing at him unexpectedly.

"Nemamiah," Castiel greets his brother, as his brother appears before him, using a young priest as a vessel. He wonders if his brother is happy to see him, or if he came just to taunt Castiel. But then again, Castiel probably deserves it.
"Castiel," Nemamiah asks, "Why did you call?"
"I need you to kill me," Castiel says, "But not right now. In January 1979, please." Castiel knows it is a high order; it was over forty years ago, and that's a high order on an angel's grace. "Castiel-" Nemamiah begins, but Castiel interrupts him, "I know it's a lot to ask, Nemamiah, but you must."
"Why?" Nemamiah frowns. Castiel knows that Nemamiah cares about him, even after Castiel fell, and knows that it's a difficult thing to ask him to do. "For justice, Nemamiah, because I killed righteous man," Castiel looks down, ashamed by what he had done. After all, if he had never met Dean, then Dean wouldn't have died. Nemamiah assures him, "You didn't, Castiel. But if you truly wish for me to do so, then I will. Are you sure?"
"Yes, it's the only way I can save Dean."
"You are not aware of the consequences, Castiel. Meddling with time is dangerous. If you never meet Dean Winchester, it could lead to a number of things." Castiel is fully aware of the consequences; he's had a lot of time to think over them. He travelled through time regularly when he was an angel; some said that he was one of the best at it in his garrison. "I am aware, Nemamiah, but anything is better than a- than a-" Castiel can't bear to say that Dean is dead, so he finishes with, "than Dean not being here."
"Why January 1979?"
"The 24th January, actually," Castiel says, hoping that will explain enough for Nemamiah.
When Michael's true vessel had been born, in Lawrence Memorial Hospital to John and Mary Winchester, many angels had visited the newborn. Castiel, along with Uriel and Anna, had been one of the many, and had taken the vessel of a young trainee doctor, who was also the uncle of his old vessel, Jimmy Novak.
Nemamiah had been one of the few that stayed in Heaven, busying himself with his own job.
"The date of Dean Winchester's birth, of course," Nemamiah says. There's a beat, before Castiel asks, "Will you do it, brother?"
"Yes," Nemamiah answers. "I hope it's worth it," he says, before vanishing into thin air.

Castiel's eyes widened and Sam stared at him anxiously. "I know how I got here," he muttered.
"How did you?" Sam's eyes were full of curiosity. Castiel knew this meant telling Sam of Dean's death, so he decided not to.
"I don't want to talk about it," he said. Sam nodded, understanding, and Castiel turned to look out of the window.
There were abandoned shops along the road; some burnt, others with objects knocked to the floor, it was could only be assumed in the rush of the residents fleeing.
"Look," Sam said suddenly, pointing at an old factory on the edge of the town, "Lights." The others all stared at it, a glimmer of hope erupting in the car. "I can't believe it," the man sitting next to Jim said, "More survivors!"
"D'you think we'll need guns?" Jim asked, gesturing to the trunk, which was filled with about every weapon you could imagine. It reminded Castiel of the Impala, though much less organised than it had been when Castiel had tidied it up after the end of the apocalypse.
"Take them just in case, but no shooting," Sam ordered, and the men nodded as the car pulled up onto the car park, and stepped out of the car. Sam grabbed a walking stick on the floor of the car, and stepped out, as a figure began to approach them. Castiel helped the two other men take out the guns, and Sam walked over to the man approaching them. He heard them talk, but didn't look over, as he slipped a gun into his pocket. It had been a while since he picked up a gun.
As he looked up, he noticed that Sam was walking towards the car with-
No. It couldn't be him. He couldn't believe he'd saved him. He rubbed his eyes, but the figure remains.
He whispered, the ghost of his past weighing heavy on him, as Sam and the figure walked over to him, "Hello Dean."