Based on a post I found on Tumblr:
"What if when Dean dies, his soul becomes attached to baby because he's lived in that car for years? It undoubtedly holds tons of his DNA, and it's his most prized earthly possession.
"What if the only way for Dean to move on… is to burn Baby?"
(tnbcaddict . tumblr post/59179446374/what-if-when-dean-dies-his-soul-b ecomes-attached)
Warnings/Triggers: Major character death, feels!
Dean had died on a Tuesday, much to his brother's frustration. It had been two decades since the endless Tuesday, but Sam never lost those memories. At least he had the comfort of knowing that this would be the last time he would have to witness Dean's death.
It was surprisingly normal, compared to the majority of their lives. A blood clot, of all things, in the middle of the night. No monsters, demons, or angels; not that they had seen any in almost fifteen years. It was almost peaceful, in comparison. Sam didn't quite understand all the medical terms, but the doctors had said that Dean felt no pain and went quickly. It was a comfort to Sam's ears, since he wasn't there in his older brother's last minutes.
Sam had moved out of the Men of Letters bunker soon after there were no more beings to hunt. He had floated around for a while, before settling down with a lovely woman named Brooke. They were only a day's drive from the bunker, so the two visited quite often.
Cas and Dean never left the bunker. It felt natural to them, to be all alone, together. They told Sam about their relationship a few months after he left.
When Sam got the frantic call from Cas that fateful Tuesday morning, he was in the car within two minutes and speeding down the highway to the bunker. He made the trek in a record six hours, though Dean was long gone by the time he got there. He pulled up to the hospital to find Cas sitting on the curb, staring into space. They drove back to the bunker.
They had Dean cremated, as they had lived as hunters for far too long to have it any other way. A few weeks after his death, Sam found an apartment near his own house and convinced Cas to leave the bunker. There were too many memories, and since becoming human Cas had always been a bit weepy. He agreed, so they packed up, and left the place that had been home for so many years. As Cas took a last look around the bunker before he shut the door behind him, his heart ached at how empty it was.
It took a while, but Cas finally settled into the apartment. He found himself a job at the local museum, which was perfect. He loved sharing stories he had lived through as an angel to the visitors. His favorites were teachers bringing their classes on field trips. The kids loved him as well.
One day, Sam burst into the apartment, a huge grin on his face. He announced that Brooke was pregnant. The two men celebrated, and Cas could hardly contain his excitement. He was going to be an uncle.
The months went by, and, eventually, Robert Dean Winchester was born. Bobby Dean, for short. Cas took him on his first trip to the museum on his first birthday. He told the boy all the regular stories he told the museum-goers, but added his own twist to everything. He told him about all of his memories from being an angel, so long ago, and about Dean, the boy's namesake.
The haphazard Winchester family, Castiel included, had somehow fallen into a sense of normalcy.
Dean came back on a Tuesday, much to his family's frustration, and the first words out of his ghostly mouth were, "Fucking finally, Sammy! I've been working my ass off for who knows how long trying to get you to see me!"
"All right, Dean, you gotta tell us what's up." Sam, Cas, and Dean were sitting around the dining room table in the apartment. After about a week, the two living Winchesters had convinced Dean to discuss things with them. "Why the hell are you here, bro?" Sam asked. "You know how important it is you go on to heaven."
Dean rolled his eyes. "You think I don't know that? But what are the chances of me going to heaven? Me! Dean Winchester, of all people. You'd think I'd have a one-way ticket to hell."
"If I recall correctly, you were actually guaranteed access into heaven, Dean," Cas told him. "That was decided upon a long, long time ago. We even discussed it a few times, before..." he trailed off.
The three sat in silence for a moment. "Well, yeah," Dean mumbled. "I guess that's right. But I just..." he sighed. "I don't know. I couldn't just leave you guys here by yourself. I couldn't... I couldn't leave you, Cas."
"Dean, we weren't alone," Sam insisted. "We had each other. As much as you hate to admit it, the world keeps going without you in it."
"Ha ha, very funny, Sammy."
"It's true," Cas added. "As much as it... hurt... immensely, to have you gone, life has gone on. It still hurts, occasionally, but now I can smile when I think about you, instead of cry."
Dean felt tears in his eyes, but smiled past it. "Still my weepy fallen angel, Cas, aren't you?"
They let Dean hang around for another week or so, until Sam finally decided that it was time for the visit to come to an end. Dean had gotten to officially meet his nephew, had gotten to spend time with Cas, and had gotten to pal around with his brother again, but enough was enough.
"C'mon, man, you gotta tell us what you're attached to."
"Nope. Not saying."
Sam groaned and rubbed his temples. "Dean. This isn't good for you. You need to move on."
"What part of little brother don't you understand, little bro? I'm old enough to make my own decisions."
"Dean, you're dead! I'd say you don't have the mental capacity to make your own decisions right now!"
"Shows what you know."
"Tell me what you're attached to, or Cas and I will start burning everything that's left of yours! Jesus, Dean, why do you always make things like this so difficult?"
"Because I thought it would be obvious! It sure was to me!"
"What do you mean, obvi –"
The two stared at each other. Dean was right. It was obvious.
Sam drove the Impala to an old, abandoned airstrip, where nothing else could catch fire. Dean, of course, rode in the passenger seat, and Cas followed behind with Sam's truck. When they were parked, the three got out and stood by the Impala, just staring at it.
"I never thought I'd live to see the day," Dean said. "Well. Figuratively speaking, of course."
Sam picked up the gas can sitting by his feet and froze for a second before starting to douse the car. Each splash to hit the paint or to go through the open window onto the upholstery sounded as loud as a gunshot. When he finished, he pulled out a simple silver lighter.
"I guess this is it," Dean said softly. "I mean. You guys have said... goodbye before. I never..." He closed his eyes and took a deep breath. "I'll miss you, that's all."
Cas stepped forward and reached out, as if to stroke Dean's cheek, but his hand passed right through the ghostly form. His lips formed a silent "Oh," as he remembered. He withdrew his hand. "We'll miss you, too, Dean. We always will. But, sooner or later, we'll be up there, too. You just have to save us a spot, all right?"
Dean nodded, the tears falling freely. "Light it up, Sam," he said without taking his gaze from Cas's. "Just a regular old salt and burn, right?"
"Right," Sam said, his voice cracking a little. He flicked the lighter and, after a moment's hesitation, tossed it into the Impala.
I was sent to heaven on a Tuesday. At least, I think it was a Tuesday. As it turns out, dying a second time doesn't hurt so much. I mean, the first time didn't hurt so much either. I wasn't there for the doctors and such, but Sammy told me that it was a blood clot. Quick and painless. Seemed to make him and Cas feel better, at least, so I thank whoever's watching over us for that.
As the Impala burned, I could almost feel the flames gathering at my feet. For years, I had watched ghosts go up in flames, but never even spared a thought for what they must be feeling. I don't know if only the violent spirits are in pain or what, but there was no burning sensation or anything.
I probably should have watched Baby burn. I mean, she's my baby. Forever and always. But I didn't. I watched Cas. I watched his face, and he watched mine. Damn, did I love that angel. And I wanted to make sure, no matter what, that his face was the last thing I saw before I