Author's note: I don't own Supernatural or any of the characters. That's Kripke's playground and I'm just messing in the sandbox. This is what my brain created after I stopped being a sobbing mess following this episode. Scenes/dialogue are true to the episode as much as possible, but again, not mine.

Cas caught a movement out of the corner of his eye from where he sat cross legged on the floor, explaining to the four beautiful women across from him that total perception was only attainable through, ahem, physical means. He turned his head slightly and noticed Dean had crept into his room with a strange look on his face.

"Excuse me ladies, I think I need to confer with our fearless leader for a minute," Cas said to the group. "Why not go get washed up for the orgy?"

The look on Dean's face became one of confusion.

Cas lifted himself off the floor with a groan and stretched his arms out behind him, twisting slightly to crack his back and his neck. They popped into place as Dean approached him.

"What are you, a hippie?" Dean said.

"I thought you'd gotten over trying to label me," he said impatiently, pulling out of the stretch.

"Cas, we gotta talk," Dean said urgently as Cas turned around with a sigh.

Cas pulled up short as he faced Dean and got his first real look at the man. There were fewer lines etched in his face and more of them were laugh lines and crow's feet instead of lines of worry and discontent. His clothes were well worn but not ragged or dirty like most people's clothing had become. Washing machines and dryers were a luxury nobody had time for these days.

But the man's eyes were what gave Cas a strange sensation in the bottom of his stomach, a feeling that he hadn't felt in close to five years now. The familiar green eyes still had a sparkle of life left in them, still believed that things could be set right. Still hoped.

"Whoa, strange," Cas murmured, eyes widening as he looked the man up and down.

"What?" asked Dean.

"You," he stated, tilting his head to the side. "Are not you. Not now you anyway."

"No! Yeah, yes. Exactly," said Dean forcefully. Cas could see that the man was still trying to wrap his head around something. A feeling of apprehension joined the butterflies in the pit of his stomach and Cas didn't understand why.

"What year are you from?" Cas asked.

"Two thousand and nine," he replied.

Cas let out a huff as he considered Dean's answer. That makes sense. He certainly isn't acting like he usually does around me. Another feeling joined the growing mess of sensations in his stomach, this one a feeling of loss and Cas wondered about why now, of all times, he was mourning the changes in his oldest friend. Even after all these years, he still had difficulties sorting out emotions sometimes.

"Who did this to you? Is it Zachariah?"

"Yes."

"Huh," he said with his thumb and forefinger on his chin. "Interesting."

Cas considered why Zachariah would have interfered in the life of a human, much less that of Dean's. Zachariah knew Dean's importance as Michael's Vessal but Cas knew that if the angels had had no need for the man, he would have been punished for his insolence.

"Oh, yeah, it's friggin fascinating," Dean said impatiently. "Now, why don't you strap on your angel wings and fly me back to my page on the calendar."

Cas turned away with a snicker, hiding the bitterness in his eyes from Dean.

"I wish I could, just uh, strap on my wings," he laughed bitterly. "But uh, I'm sorry. No dice."

Dean was staring at him like he'd grown horns. "What are you, stoned?"

"Generally, yeah," Cas said.

Dean looked taken aback by the serious look Cas gave him.

"What happened to you?" Dean asked.

"Life," said Cas.

What happened to you?

Dean's voice echoed through Cas' head as he downed a shot of absinthe.

Life, that's what, he said to himself. And life's just one big disappointment after another.

He shook his head and poured himself another shot. He knew Dean frowned on the drinking and the drug use, but his tolerance level was still higher than most people's. Another useless remainder of my angel mojo. Besides, ever since that day in Detroit Cas has had to keep himself carefully medicated to be of any use to anyone. He's still barely of service but at least Dean hasn't kicked him out yet.

There had to be a reason for Zachariah to risk Past Dean's life by transporting him to this hell on Earth. There was something the angel wanted to make sure Dean understood.

He remembered how stubborn the man used to be, in the days before the Apocalypse. He had fought against his fate, choosing to make his own destiny and to save his brother from his. Dean had been so full of arrogance and stubbornness; you could see it in his eyes.

Dean.

The memory of those hopeful green eyes sent a wave of loss coursing through his veins. His heart constricted painfully and the air around him refused to enter his lungs. His Dean. The old Dean. The one he had given everything for.

Cas downed another shot.

That was the man he would have betrayed Heaven and Hell to protect. The man he had battled the forces of Hell to save and raise from perdition. The man he had given everything for. The man he loved more than creation itself.

Dean of 2014 wasn't that man anymore.

Cas downed another shot.

He wasn't sure exactly where things had started to go wrong between them. It might have been the unsuccessful search for the Colt or anything else that could help them kill the devil. It could have been the night Ellen and Jo died at the paws of the hellhounds. It could have been the time Bobby was possessed by a demon and was forced to stab himself to be rid of it, but was left paralyzed. It could have been any number of failed missions and hunts gone wrong that started the decline between the trio.

But Cas knew the exact moment when everything changed forever, because the moment is burned into his memory.

It was the same moment Dean's eyes had became dull and hard. The moment that Dean and Cas ceased to be anything, much less anything more than friends.

It was the moment Cas failed Dean. The moment Sam said 'Yes' to Lucifer.

That was the moment that broke them both.

Protect Sammy, Dean had said to him before the confrontation in Detroit. Whatever happens, protect Sammy.

He had agreed but promised himself that Dean came first when the time came to save the Winchester brothers. He knew he was being selfish, but in their combined arrogance they didn't believe they could fail.

In the end it didn't matter. Castiel watched helplessly from the ring of Holy fire he was trapped in as Lucifer's vessel tortured Dean until Sam said yes. As the demon took control of his brother, Dean couldn't even summon the words to allow Michael into his body, knowing that he would have to kill Sam to save the world. Castiel watched as the fight went out of his body and the light went out of his eyes.

In the end, he failed them both.

Cas downed another shot.

In the moments following Lucifer's ascension in Sam's body, Castiel felt the Host around him withdraw from Earth. Hoping the heavenly army was regrouping somewhere for a final attack, Castiel jumped across the dying ring of Holy fire without thinking and ran to Dean. Throwing himself between the semi-conscious man and the body formerly known as Sam, Castiel threw up his hands as a ward against attack.

Lucifer snickered at the feeble gesture. Oh, come now little brother, he said with a sneer. We aren't so different, you and I.

And Castiel felt himself lifted and thrown across the warehouse into a wall. Crashing to the ground, his vision flickering black Castiel tried to pick himself up. With horror, he realized he could not put weight on his left leg, and he could not summon the energy to heal it. Lucifer smirked. Looks like hanging out with the Winchesters can make you stupid, he said. But it seems like you've finally figured it out. Bye-bye Angel Radio. And with that he disappeared, leaving Castiel and Dean alone in the warehouse. Without Sam, without help and without any of Castiel's angel mojo.

Castiel was mortal now.

Cas downed another shot.

That was the moment he became human and the moment he lost everything in his life. He had come to accept his failure, albeit through the haze of booze and pills to numb the pain of losing Dean and his Grace. There still felt like there was an emptiness behind his shoulder blades where his wings used to be and a physical hole in his chest where his heart should be, that when he had looked into Past Dean's – his Dean's – eyes, ached painfully.

Cas' eyes widened as he realized what Zachariah intended to show Dean. He wanted Dean to see where his choices would lead, and what would become of the world if he continued to deny his destiny.

But that was where Zachariah made a fatal mistake; he didn't know Dean like Cas did.

And Cas knew there was no way that Dean would submit to Michael.

It was always going to end up like this.

Cas went to pour himself another shot and found the bottle empty.

So instead he just put his head in his hands and cried.

Cas kicked his feet up onto the table and poured himself a glass of beer while listening to the exchange between Dean, his second-in-command Risa and Past Dean. Past Dean was mostly just making smartass comments and Cas laughed to himself, still mostly drunk from the bottle of absinthe.

"So a demon tells you where Satan's gonna be and you just, believe it?" Risa asked skeptically.

"Oh, trust me," Dean said with an unpleasant grin. "He wasn't lying."

"And you know this how?" she said, voice rising with frustration.

"Our fearless leader I'm afraid, is all too well schooled in the art of getting to the truth," Cas interjected.

There was a pause in the room.

"Torture?" Past Dean said incredulously. "Oh so, we're torturing again?"

He took a deep breath and exhaled.

"Well that's good. Classy."

Cas snickered again and slowly realized he had been staring at the younger man while he spoke. Embarrassed he turned to find the other Dean glaring at him.

"What?" he said with what Dean would have called a 'shit-eating grin' on his face. "I like past you."

Dean rolled his eyes and continued explaining his plan.

"Lucifer is here. Now. I know the block, and I know the building," he said.

"Oh, good. It's right in the middle of a hot zone," Cas said sarcastically.

"Crawling with Croats, yeah," Dean said, with a hint of anger. "You saying my plan is reckless?"

"Are you saying we, uh, walk in straight up the driveway past all the demons and the Croats and we shoot the devil?" he countered.

"Yes." The look on Dean's face sent an icy cold finger of dread running down Cas' spine.

"Ok," he said, rolling his eyes. "If you don't like reckless, I could use insouciant maybe."

"Are you coming?" Dean asked.

Cas took a deep breath.

"Of course," he said, looking over at Past Dean. "But why is he? I mean, he's you five years ago. If something happens to him, you're gone. Right?"

Cas knew exactly why Dean was insisting that his counterpart be involved. Dean wanted to show his earlier self just how bad the world had gotten, wanted to show him where his decisions had taken them all. He needed Past Dean to know how much he regretted his fight against the angel's plan. Because even though Dean was terrible at talking about his feelings to other people, he was even worse at acknowledging them to himself.

"He's coming." Dean said decisively.

"Ooooooh-kay," Cas said, trying to keep the fear and frustration out of his voice as he rose from the table and headed out the door. "Well, we'll get the grunts moving."

"We're loaded and on the road by midnight," Dean called after him.

"Alrighty," he returned, headed out into the night and the safety of the darkness. He didn't want Dean or Risa or hell, his Dean to see the tremors that had started. He didn't want anyone to see how terrified he was or worse, give away Dean's plan. Because he knew the look on Dean's face and the way he got defensive when Cas questioned him. Dean is upset about something and that could only mean one thing: Dean wasn't counting on anyone – himself included – on surviving this mission.

Cas was secretly pleased that Past Dean had chosen to ride in the Jeep with him. Pleased and absolutely wrecked at the thought of being cooped up in a vehicle alone with the one thing he missed the most in the entire Universe. It was a combination of feelings that made his head ache and his stomach roll. Plus, he had drunk an entire bottle of absinthe to himself.

He grabbed the bottle of pills he kept on the dashboard, popped the top and tossed a couple in his mouth.

"Let me see those," Dean said, reaching for the bottle.

"You want some?" Cas offered, clearing his throat as he downed the pills dry.

"Amphetamines?" Dead asked.

"It's a perfect antidote to that absinthe," he said, nodding.

Dean continued to stare at the bottle incredulously for a moment before turning to the window.

"Don't get me wrong Cas," Dead started. "I, uh, am happy that the stick is out of your ass but what's going on? What's with the drugs, and the orgies and the love guru crap?"

Cas threw back his head and laughed at Dean, nervous energy combined with the Adderall bubbling out of his mouth.

"What's so funny?"

"Dean," he said, tone turning serious. "I'm not an angel anymore." I am no longer the angel Castiel. Just the human Cas.

"What?"

"Yeah I went mortal."

"What do you mean? How?" The incredulous look on Dean's face would have been adorable if it didn't drive a stake through Cas' heart. Dean hasn't looked at me with that much concern in longer than I can remember.

"I think it had something to do with the other angels leaving but um, they bailed and my mojo just kinda… drained away," Cas said with a gesture of his hand. "And now, I'm practically human."

He paused.

"I mean Dean, I'm all but useless. Last year – broke my foot. Laid up for two months."

"Wow."

"Yeah."

"So you're human," Dean repeated back.

Cas nodded his head, good natured smile on his face betraying the anguish he felt inside. It isn't fair, he thought. I gave everything. Everything. And now I have nothing. I can't even help Dean like before. I'm just a liability now.

"Well welcome to the club," said Dean as he turned away.

"Thanks," Cas said, bitter taste in the back of his throat. "'Cept I used to belong to a much better club. I'm now powerless. I'm hapless. I'm hopeless."

What am I saying? he thought to himself. Shut up Cas.

"I mean why the hell not bury myself in women and decadence?" he continued, internally horrified that he couldn't stop talking. That would be the amphetamines kicking in. "Right? It's the end baby. That's what decadence is for. Why not bang a few gongs before the lights go out?"

Dean sat in the passenger seat and stared dumbfounded while Cas grinned from ear to ear.

"I mean, that's just how I roll."

Cas laughed at the idea. The amount of women he had had sex with since turning human would have been enough to impress the Dean of old, but they meant nothing to him. It was a quick deal; means to an end. They weren't even his type, although to be fair Cas had never had a type other than Dean. And that ended in Detroit.

He always made sure they were gone before he fell asleep. He couldn't bear waking up beside someone who was warm and pliable and molded to fit his body. The one he loved was solid and hard underneath his fingers and as unyielding as his personality sometimes and yet somehow, they fit together like they had been made to. He did not want to wake up next to someone who wasn't Dean.

Nor did he want them around when the nightmares hit.

He didn't want to explain that every night he watched Dean on the rack again, Dean being tortured to coerce Sam, Dean dying over and over again because he was powerless to save him. He did not want them around when he woke up screaming.

And he certainly did not want them around to watch him cry himself back to sleep.

The convoy reached the edge of the hot zone and continued in on foot toward the abandoned sanitarium where Lucifer was said to be. Cas tried to listen to Dean as he outlined the ambush but all he could hear was the blood rushing past his ears. White noise blocked out everything and he nearly dropped the binoculars that Dean handed to him. He tried to draw a deep breath to keep from panicking but his chest felt too tight. This is it, he thought. After all these years this is how it's going to end. A suicide mission to kill the devil.

He wasn't afraid of dying. Ever since Detroit, Dean seemed to have a death wish. He was foolish and foolhardy but Cas would follow him anywhere. He knew Dean was more capable of protecting himself than he was but still he would never let him go alone, no matter how dangerous the mission. I don't want to live in a world where he doesn't exist.

No, the panic he was feeling was not for himself, or Dean, or Risa or anyone else in their group. It was for the time traveler – my Dean – who was being forced into this situation. Cas' feelings of protection welled up inside of him until he felt like he would burst. This Dean still has hope, he still believes. And that must be protected.

Still, Cas was ever the good little soldier who knew how to take orders, especially when they came from Dean. So he kept his mouth shut and tried to pull it together.

He let out a sigh of relief when Dean knocked Past Dean out and ordered the group to move forward. With any luck, he would be safe out here. Or safer than anyone else, at least.

The group scaled the building and entered the building through the second story building while Dean snuck around. There were no illusions, everyone knew they were being used as a distraction but so few of them had anyone left to live for that they willingly sacrificed themselves to buy Dean time. But they made sure to take out as many of the demon bastards as they could before they fell.

Cas crouched behind an overturned desk for cover as he sporadically fired shots at the demon lackeys who were advancing towards their dwindling group. Risa had been surprised from behind and Tom had had his throat ripped out when he tried to save her. There was just a few of them left and they knew they weren't going to hold out much longer. They were waiting for a sign that Dean had succeeded.

He felt the bones break in Dean's neck as if they were his own when the devil in Sam's body stepped on his throat. Shock blinded him as he processed what had happened.

He's gone.

Pain and anguish built up inside him until he was screaming Dean's name out loud, tears streaming down his face. He fired rounds over the desk until he was out of ammo and then stood up and rushed towards three of the demons who were advancing. Shouting an exorcism in Enochian and throwing punches at the temporarily stunned demons, Cas managed to send two of them back to Hell before they fell upon him, ripping and tearing him limb from limb. Cas fought back as his strength left him, Dean's name on his lips like a prayer, until there was nothing left. The floor was red with the blood of a former angel, and the demons laughed as they ripped apart the remaining fighters. Cas laid in pieces on the floor as his mortal life left him. He managed a weak smile before he died.

I'm coming Dean.

Five years in the past, Dean claps a hand on the angel Castiel's shoulder.

"Don't ever change," he says.

Castiel's chest constricts with a strange feeling of loss and anguish that spoke of years of hurt and loneliness. He wonders where the feeling had come from. But it lasts only a moment and then Castiel thinks of it no more.