Disclaimer: I do not own Supernatural. Otherwise, Destiel would have been acknowledged as canon in season 5.

My Immortal

From the moment that Metatron was defeated and placed in jail, Castiel knew he couldn't stay in Heaven.

Now that he thought about it, Heaven had ceased to be the place for him a long time ago. And no matter how he tried to help it, to fix it, all he ever ended up doing was making it worse. Causing the angels to fall last year was really the final nail in the coffin.

It didn't help that the grace within him was also starting to sputter out. Cas couldn't kill another angel just so he could live. Not only did he not care enough to live, he had long ago gotten tired of the killing. And if he was to die, then he would prefer it to be someplace he actually loved to be: Earth. Though it did not feel like home as much as had.

Dean was dead. There was nowhere in the universe that would feel like home.

Castiel looked around the park where he was currently sitting. It reminded him of another park in another time, what seemed like a long time ago, where he had first opened himself up to the Righteous Man, no, to Dean Winchester.

Given what he had learned from Naomi, it hadn't been the first time he was doubtful or disobedient, but he was sure, despite his lack of memory from Naomi's meddling, that it was the first time he admitted it to someone.

Dean… Castiel felt a throbbing sensation in his chest that had nothing to do with his waning grace. He stood up from the bench and walked back to his car.

Everything was reminding him of Dean. He wished it would stop, but somehow he knew that time would never erase the pain he was currently feeling. It's not like he had much time left anyway.

Castiel had no idea why he was still alive.

Naomi had perhaps been right when she said he couldn't die properly, but he preferred to think that Dean had been more correct in saying that he was brought back to fix what he had broken. In that case, Cas had done all he could. The angels were back in Heaven and figuring things out. Metatron would face his crimes. Abbadon was dead and Crowley was most likely busy sorting out Hell. Earth was relatively safe.

Then why was he still here? What more could he do?

He was barely an angel: he had started needing to eat, drink, and sleep. Not as much as a human, but still. When his grace was gone, he also would be gone. By Castiel's calculations, it should have burnt out by now. It would be better for everyone if he was gone, and Dean was no longer around to even try telling him otherwise.

Dean… Castiel put down the bacon cheeseburger he had been eating for a second, and took a sip of his chocolate milkshake. While he had been human, he discovered he had a bit of a sweet tooth (and remembering Gabriel and his time with the bees, he wondered if it was some sort of angel thing). Picking his burger back up, he found his thoughts turning, as they always did, back to his human.

That's right, his human. Metatron had been right. Everything he had done, since first laying eyes on him in Hell, had been for him. Hester had been right as well as saying he had been lost to Heaven since that moment.

Castiel loved Dean Winchester. He didn't just love him; he was in love with him. Dean was the one he had fallen for, in every sense of the word.

Cas had always had a fondness for humans, finding them fascinating, and had enjoyed watching them over the millennia whenever he had not been fighting on Heaven's behalf. So, yes, he did love humanity, but, out of all the humans he had watched over and met, he knew he was in love with Dean.

Castiel had never really tried to hide it. Heaven started watching him because he couldn't even try to hide it. He had told Dean that he fell for him and that they shared a profound bond. He had told him that he did everything for him. It wasn't really a secret.

So, everyone seemed to know his feelings. When Heaven, Hell, and Earth agreed on something, you know things are serious. Uriel, Alastair, Anna, Michael, Lucifer, Bobby, Ellen, Jo, Crowley, Meg, Raphael, Balthazar, Rachel, Hester, Inias, Naomi, Kevin, Sam, Charlie. All of them knew the truth. Sometimes Cas could tell they knew just by the looks they would give or side comments they would say. The only one who had ever actually asked him about it was Sam.

One day during the Apocalypse, he and Sam had been by themselves in a motel room while Dean had been out getting food. At that point, it was even rarer for the two to be by themselves. It wasn't like they weren't becoming friends; it's just that Dean was their common ground.

"Hey, uh, Cas?" Sam had awkwardly asked as Cas had tried using the laptop to come up with new locations to search for God.

"Yes, Sam." Castiel had looked up at him.

"Are you, um, in, uh, love with Dean or something?" Sam had looked way out of his comfort zone. He had then tried to explain himself in a rush of words. "Because, with the way you look at him all of the time, and helping us. I mean, it doesn't seem like there's much for you here, but you still show up when we need you. You're losing your powers, and, uh, well…" He trailed off, grimacing.

"Yes." Castiel had never really believed in beating around the bush, and he saw no reason to deny the truth.

Sam had blinked, surprised by his blunt answer. Then, he grimaced again. "Does Dean…"

"I would assume not, considering he took me to a den of iniquity." Castiel had looked back down at the laptop and frowned. Computers were really not his things.

"A…" It had taken Sam a few minutes to realize what he had meant, and then the bitch face came out. "Dammit, Dean." He ran a hand down his face, both due to his brother's obliviousness and sheer audacity to take an angel to a brothel. Sam had looked back at the fallen angel with a hint of pity in his eyes. "And you're alright with this?"

Castiel had looked back at him, and saw Sam's worry. He gave him a slight smile. "I…" He had paused, looking for the right words. "I neither hope for nor expect my affections to be reciprocated, Sam. I would not wish to put any more pressure or burdens on him unnecessarily. I also do not wish to put our friendship in peril. This is enough for me."

Sam had looked skeptically at him. "And that won't change? Most people would want more."

"I am not most people." Castiel had closed the subject, and with a final look of pity, Sam had as well.

The younger Winchester had brought up the subject a few times after that, though a word was never said. Usually, Sam would just look at Dean and then him, and raise an eyebrow. And Cas would give his answer with his eyes. Always.

Dean never figured it out surprisingly. Dean was smarter than he thought of himself and very observant, but he never seemed to notice Castiel's regard for him.

It didn't really matter. Even now, Cas still didn't expect his feelings to be returned, though he still showed them in the only way he knew how. Human romantic gestures had always seemed trite and fleeting, so he had shown his love the angel way: by devoting everything to Dean, by giving everything for Dean, no matter the cost to himself. That was all he could do.

Of course, Dean was dead, so it mattered even less.

Still, Cas continued to think, if Dean is gone and there is nothing left that I can atone for, then why am I here?

"Is there anything else I can do for you, sweetie?"

Castiel came out of his contemplations and looked up at the waitress. She had noticed that he was finished eating. "Uh, yes. Do you have any pie?"

"Sure thing, sweetie. We've got cherry, apple, and pecan." The waitress, Jillian according to her nametag, gave a kind smile.

"Then, I'll have a slice of apple, please." Cas gave her a small smile in return. Though his was sadder.

"Coming right up." Jillian quickly turned on her heels and went back towards the kitchen. She swiftly returned with the slice. "This one will be on the house. You look like you need it." She gave him a smile again, and Cas found himself once again in awe at the kindness of humanity.

"Thank you." He nodded his thanks to her as she went to wait on a different customer. Castiel turned towards his pie. He did enjoy the treat, though he thought honey was even better. Still, whenever he went to a diner, he made sure to eat a slice in Dean's honor.

"Hey, Cas." Cas looked up at the familiar voice. Sam gave him a small smile as he slide into the seat across from him.

"Hello, Sam." He replied, taking a closer look at his friend. Sam seemed more… hardened than he had ever seen. The kindness that normally lingered on his face was almost gone, the way it had during his blood addiction and time without a soul. If this was what Dean's death had done to him, then Cas couldn't help but wonder if he had come out better from the loss.

He also wondered how Sam found him as they had not contacted each other since he and Gadreel snuck into Heaven.

"So, how are things up in Heaven?" Sam asked. "I mean, I was passing by and saw you here, so I thought I might as well stop to chat."

"Metatron was captured and his plots revealed. Hannah and the others have opened the Gates and are reorganizing Heaven." Cas said as he ate his pie.

"Uh, that's good at least." Sam looked off into the distance. "I guess you decided not to join them."

Cas stared at him, his answer obvious.

"Are you, uh, are you doing okay what with your grace and all?" Sam continued, his face now showing the concern and kindness that Castiel was more familiar with in regards to the younger Winchester.

Cas found himself looking down at the remains of his pie. He didn't want to see any pity over his state.

"Couldn't you do the same thing again? I mean," Sam tried to find a solution, but he was really grasping at straws.

"No, Sam." Castiel looked him in the eyes, adamant.

"Jeez," Sam sat back and ran his hand over his face. "It's just – you're my friend so I don't want to lose you. And I haven't found Dean yet, so-"

Cas found himself confused. He tilted his head as he asked, "Find Dean? What do you mean?"

Sam stared at him. "He disappeared, so I have to find him."

Cas felt a swell of worry come up. Denying the truth like this, he had been led to believe, was neither healthy nor right for humans to do. Although he wished he could live in such a state of denial. "Dean's dead, Sam." He tried to say this gently.

Shock crossed Sam's face. "You don't know." Sam's face crumpled with sadness. "I thought you knew. I'm sorry, Cas."

"Know what?" Cas tilted his head again.

Sam leaned in and lowered his voice. "Dean's alive, Cas. I swear, he's alive, but he's disappeared."

Cas stared at Sam. He wanted to believe it. Oh Lord, he wanted to believe it. Down deep in his grace, he felt a spark of something. But Cas couldn't believe it quite yet. It sounded too good to be true. Also, when it came to the Winchesters, there was always a catch.

"What else, Sam?" He asked quietly, pushing aside his empty plate and leaning in.

A flash of pain came into Sam's eyes. "He's alive, but…

"Dean's a demon. The Mark turned him."

The spark became a blaze.

Dean was alive.

Dean was alive!

A demon, sure, but alive!

Cas could work with that. He now knew why he had not yet died.

"I'll help you." Cas told Sam, and he was happy to see a genuine smile on Sam's face.

There was one more thing for Castiel to fix.

Angels need a purpose to survive.

This is important for all angels, but especially those who do not remain in Heaven. After all, in Heaven, angels automatically have the purpose of being soldiers and workers, following orders, and doing whatever job God has gifted them. For those who have left Heaven, angels tend to find their own purpose or mission. Gabriel found his purpose in being a Trickster. Balthazar had found meaning in taking part in the human high life and being a thief. Castiel had first found purpose in helping the Winchesters stop the Apocalypse and finding God, and when he later returned to Earth, he had tried to help people as part of his penance. While he was human, he still found a purpose by trying to do his best at his job and helping others.

Since his latest leave of Heaven, he had really had no purpose. He had wandered, helped people, contemplated his soon death, and simply done his favorite pastime of watching humanity. He had felt lifeless without purpose. He really had no reason to even move. It had felt like his grace had already gone out, especially since he thought that Dean was gone.

Sam changed that with his news.

Castiel felt the thrill of purpose, of a reason to exist, fill him. He would help him find Dean, and they would save him.

Sam planned on using the same demon cure he had mostly used on Crowley, explaining the logistics to Cas. He didn't know if it would work due to the Mark, but he figured it was worth a shot. The Mark was the reason that Cas was dubious that it would work. They didn't just have to turn Dean back into a human, they also had to free him from the power of the Mark or it would just happen again. That would need more power than the demon cure would provide.

So Cas delved into what he knew about the Mark and its effects and what else could be learned about it. He looked into how demons were made, the nature of souls. He looked into this while at the same time reigning in Sam. Sam was ruthless in his attempts to find Dean, and that scared Cas to see one of his kindest friends turn so dark. He knew Dean wouldn't like it if he were normal, so he tried to stop Sam from becoming the monster people had always said he'd become.

It was hard, but it was the sort of mission that Castiel needed.

Along the way, he picked up an interesting fact: Dean and the First Blade would not be truly united until Dean killed his blood brother with it, just as Cain had. In other words, Dean may still be turned back as long as he didn't kill Sam.

Castiel took all of his new knowledge and came up with an idea. It was a way to save Dean, though the personal cost was high. Sam would never go for it though, so Cas kept it secret and went along with Sam's plans.

Then, they finally found him.

The Impala pulled up to a barn in what appeared to be the middle of nowhere.

"So, apparently, he's torturing someone in there." Sam said as he opened up the trunk and started picking up the demon handcuffs and other supplies to hold Dean during the exorcism. "Don't know why, but we've finally got him. I want you to distract him while I get these on him, so – "

"That won't be necessary." Castiel said standing at Sam's side.

"What?" Sam looked at his friend. "But – "

"Sorry, Sam. Goodbye." Sam never saw the punch coming. Normally, Cas wouldn't rely on such crude methods to knock someone out, but he needed to save what little grace he had for Dean.

Cas caught Sam as he dropped like a sack of potatoes and gently leaned him up against the Impala. He shut the trunk, as there was nothing in there that he would need, and gave one last glance at his friend.

He sighed, "If you die, all is lost, Sam. This is between me and Dean."

Castiel knew that Sam couldn't hear him, but it made him feel better to explain himself.

Cas walked to the front doors of the barn and was suddenly reminded of another barn years ago.

It's all come full circle. He thought.

Castiel pushed open the barn doors.

"Hello, Dean."

Dean's back was turned towards him. Just around him, Cas could see some poor demon strapped to a table. With a snap of Dean's fingers, the demon, blood, and torture tools disappeared. He had most likely sent everything back to Hell. Then he turned around.

Cas walked forward and studied his soul. Dean's soul had been the brightest, most beautiful soul he had ever seen. Every time evil had threatened to smother it, it would burn brighter and grow stronger. Now, the soul had twisted. It held a dark beauty to it. Most would assume that this would put Castiel off. That to see the soul and man that he loved would disgust him. How quickly people forgot. After all, when Castiel had first laid eyes on Dean in Hell, his soul had been on the cusp of becoming demonic. Cas had healed him.

And he would do it again.

A malicious sneer spread across Dean's face. "Cas, my old friend." He blinked, his green eyes turning black. "So, what brings you here of all places? Shouldn't you be fluttering off to help Heaven like you usually do?"

Cas stopped just outside of Dean's reach. "I came to see you, and in any case, Heaven no longer needs my help."

Dean snorted, his eyes flicking back to green. He pulled out the First Blade and started using it to pick blood out from under his nails. "Is that so? Just as well. Whenever you help, you only make things worse." He smirked at the angel, while caressing the Blade.

Cas looked deep into Dean's eyes. There were times when he and Dean could just stare at each other, no words required, and know what the other was thinking. This time though, Dean refused to meet his eyes all of the way. "I never thought that things would come to this." He admitted, ignoring Dean's jabs. They were true after all.

"Yeah, an angel and a demon, facing off in a barn. Guess you couldn't, huh?" Dean said, flippantly. But his smile had a glint of steel in it. "Then again, you ain't much of an angel anymore, are you?

"I can see you." Dean took a step forward and to the side, like a predator getting ready to pounce. Castiel took a step to the side, making it so they were circling each other. "You've barely got any mojo left. And when that snuffs out, well," the shark-like smile grew wider, "let's see if you actually stay dead for once."

"I know. That wasn't what I was referring to." Castiel tilted his head. "You don't remember what you were like when we first met, do you?"

Dean looked like he was about to say something, but it never came out. Cas cut him off as he took several steps forward, getting right into his personal space like he always did. Dean looked like he was a bit surprised by the sudden invasion.

"I'm the one who gripped you tight and raised you from perdition." Cas narrowed his eyes. "We have been through much together, and even though you still think you don't deserve it, I have saved you many times."

Castiel brought his right hand up to Dean's left shoulder, where he had gripped him once before.

"What makes you think that I will not again?"

He saw in his peripherals Dean slip the Blade into his chest. He couldn't worry about that now.

Because at the same moment, Castiel poured his grace into Dean, searing Dean's skin in what would surely leave a mark.

The twisting of a soul created demons. So the solution was simple. All Cas had to do was untwist and unbind Dean's soul, returning his humanity. That's basically what the ritual Sam planned to use would have done. However, the Mark was trickier. It was a cursed mark made by a fallen angel, so maybe the grace of a different fallen angel could undo it.

Lucifer had created the Mark with his hatred of humanity, his anger at God for favoring them, and his sadistic urge to tear apart two brothers who loved each other. Cain had noted that his love for Colette had brought forth his humanity, and that was what Cas was pinning his hopes on.

Castiel gave everything he had to Dean: his love of humanity, his faith that God was still somewhere, his desire for the two brothers that he had gotten close to live and thrive, and, most importantly, his love for Dean himself.

He didn't know how long it took, but he could see it working. Slowly but surely, Dean's soul untwisted, became the bright, shining star that he had gazed at many a time. He heard the sound of something shattering, and glancing at the arm attached to the Blade in his chest, he saw the Mark flare up for a single moment before fading away.

Castiel smiled.

And just like that, the final piece of his grace flickered out.

Distantly, Cas felt his hand slip from Dean's shoulder and he fell to the ground. The Blade slipped out but he couldn't see as Dean threw it away from him in horror. He could somewhat feel as Dean grasped him in a tight embrace, and he thought that he heard him shouting his name. Cas could feel his body shutting down, as every breadth was a struggle. Blood bubbled up over his lips.

But he made himself look up and he saw Dean's green eyes. He couldn't help the smile that took the last of his strength.

Cas had fixed everything, had redeemed himself. There were no more missions, no more purpose. Dean and Sam would be together again and move like they always did. Saving people, hunting things. They had never really needed him, so they would be fine. Dean would find someone to truly love. So Cas could only be glad that this time, his beloved Dean would be the last thing he saw. Especially since he probably wouldn't be coming back this time.

He felt a small ping of regret that he could not give a proper goodbye like he had with Sam. He hoped that Dean would understand though. His human had always said that he sucked at goodbyes.

Cas couldn't feel his body at all anymore and he knew that that was a bad thing. The end was near.

Then Death himself stood before him and held out his hand.

He took it with one last look at Dean. He memorized those eyes and freckles that he had often stared at. He gazed at the soul that he once held in his hands and later held in the highest regard an angel had ever bestowed upon a human.

Castiel fell, once more, into the void of death with a smile on his face.

Dean Winchester has been saved.

Continued in Never Alone.

AN: So just got into the Supernatural fandom. This is something I think could potentially happen in season 10 with some hints they've been giving and was inspired by the Evanescence song "My Immortal." I tried to make Destiel appear like they do in the show, but whatever.