Written for a prompt at comment_fic on livejournal

Notes: This is set in the 5.04 "The End"-future verse (spoilers for this episode).

That's the apocalyptic future Dean visits where he meets himself.

Future Dean will be referred to as just "Dean," but 2009!Dean will be called "past Dean."

Fic:

Dean gazed up at the night sky, at the beautiful colors seeping into the clouds due to all the ugly events. Tomorrow he would kill Sam. Or the thing in Sam would kill him.

Probably both.

Hopefully both.

It was good, though, that he would be spending his last night alone. Risa wasn't happy with him, his own doppelganger could barely stand to look at him, Chuck was chasing a lead on an undiscovered supply of toilet paper, and the others... well, the others knew that a world of hurt would fall on the poor sap who annoyed Dean with something unimportant the night before a big mission.

So it was good that Dean would finally get some peace and quiet. It was good that he would be alone on his last night. Possibly on the last night. It was fitting.

It was right.

And of course, it was apparently impossible.

Because just as Dean was about to allow himself to get a little lost, to indulge for a moment in the sensation of feeling crushed by a thousand metal blocks of regret -- just when he was about to let himself feel all the things seeing his past self had brought up, all the pain and rage that he was barely keeping down his throat -- Cas showed up.

Dean was really hoping they would get to die before having this conversation.

But Dean had seen the way Cas had looked at past Dean. And he knew that there were a lot of things that Cas had been wanting to say to him for a while, a lot of things that Cas had almost stopped caring about enough to say out loud.

Almost but not quite.

And Dean felt so tired at that moment. Too tired to look at the crazed stoner face of a desperately sad man.

Because Dean didn't really need to be reminded that he had let Cas down. He knew it already. Every human corpse they saw, every loved one crazed with loss and impotent rage, every single one of their thousands of defeats great and small: Dean knew they happened because he had let them down.

But Cas just looked at him, wistfully, and smiled. Not his usual drug-relaxed smirk. He ... almost looked serene. And for just a second, Dean thought of how Cas used to be. Before.

And Cas said, "I used to help you. When you couldn't sleep. When you were thinking of perdition and you couldn't sleep. I didn't ever tell you that, did I?"

Dean looked at him, wondering where this was going. But he answered honestly, "You never told me. But I knew."Cas let out a smile, not the doped up grin, but an actual smile for Dean. "Seeing him... reminded me."

"I figured," Dean said, knowing that past Dean would come up, ready for it.

"I remember when you used to look at me like past Dean does. Back when I was powerful and you were..."

"Nicer?" Dean said, almost smirking at the word.

But Cas let out a little snort. "You were never nice, Dean. But you were... you."

"I'm still me," Dean said testily.

"I'm not sure. But the way past you looks at me... I don't like it."

"Could've fooled me," Dean muttered.

"He looks at me like he thinks I can save him. Like I'm the same Cas who brought him from the pit, like he thinks I can still save him from something. You just look at me with... repulsion. Or regret. Or some other feeling that neither of us can afford to give a shit about. But when he looks at me like that - like if I'm here, then everything's going to be fine -- it's like ... being stabbed in the gut, you know? I tried to tell him, not to look at me like that. I tried to explain that I'm not who he thinks." Cas face was downcast, trying to puzzle out past Dean. And Dean felt a pang of something, as he was reminded once again, that Cas still was struggling to understand him, that even though they were about to die, he was still trying so damn hard.

But Dean just said, "Don't worry, they'll send him back soon, I'm sure."

"I wish he could stay," Cas said, and suddenly his gaze fized on Dean, his stare intense. There was an accusation in there, Dean knew, and he couldn't help the bile that rose in his throat.

"Well, too bad if you miss your little friend. You're stuck with me, not him," Dean said, then added, "Well, you know what I mean, you're stuck with now-me not -"

"Only for tomorrow," Cas interrupted, "Then it'll stop."

Dean stared at him, narrowing his eyes. He nodded cautiously, saying, "Yeah, if we succeed tomorrow, who knows what might change."

Cas smirked at him. "Big if."

Dean's face became stony, and he gave him a hard look. But Cas never could take a hint.

"That's why you made sure Risa hates you, right? Fearless leader? Because it's easier to lead us to our deaths now that there's no love lost?"

"You need to shut up, Cas."

"Now see, the old Dean would have never said that to me."

"Shut up about the old me! The old me is what got us into this!"

"Let me guess how it's going to go tomoorow, Dean. Fearless leader gives a speech about how we're saving the world, and then he makes us cannon fodder. Is that your plan?"

Dean's lips pressed into a thin line. "What makes you even say something like that, Cas?"

"That's your style."

"Yeah? You tell anyone else your little theory?"

Cas snorted. "And mess with their hopes on the last night? Silly Dean. Relax, I'm still going with. I can't think of a better way to get slaughtered than by you and Sam."

"He's not Sam," Dean said, wondering why he even cared enough to object.

"You know what I mean. I'm still on board with my fearless leader. I won't say a peep. I just wonder if you'll actually be able to do it."

"Are you fucking kidding me? Of course I'll be able to do it! Do you think after fucking over the world that I would even think there's a choice?"

Cas smiled again. It was some cross of bitter and benevolent that Dean hadn't seen on Cas' face in a long time. He said then, "I hope you succeed, Dean. I hope you win. It would be good for the world."

"Yeah, no kidding. Thanks for the update."

"But I won't be disappointed if you can't do it."

Dean stared at Cas. "What the hell are you talking about? We could die for this, this could save everyone, and you don't care?"

Cas folded his arms. "If you can't do it. If you can't kill Sam. If your love outweighs everything else, if there's still some part of you that can't give up, that still refuses to accept that there's no other choice-"

"There's not!"

"Well if there is..."

"Fuck you."

Cas smiled again, seeming to be happy to twist up Dean's insides until they were as troubled as his own. "As much as we need to succeed, as much as you owe it to all of us to succeed -- there's some part of me that wishes that you had it in you to refuse to kill him."

Dean answered slow through his clenched jaw, "Yeah, I get it. You would do anything to hold onto past Dean. A nice little reminder of when you had your mojo."

Cas smiled. "You're upset. That past Dean looked at you with such disappointment. With such disgust."

"He'll learn," Dean said, his tone pointing out that this was far more than a guess.

"Not in time," Cas said.

"I know," Dean answered, looking away. They both knew that there's nothing anyone could say or do or show that would convince the Dean of five years ago. There were both silent for a minute.

"You should spend tonight with him," Dean finally spoke, "Enjoy yourself with him. Leave me the hell alone"

Cas was surprised by this, this small kindness cloaked in a self-serving gesture. But he just got a look of mischief and said, "He doesn't think of me that way. Pre-apocolyptics are such prudes in bed."

Dean grimaced. It was true that people with few comforts grabbed the ones they could still have. But it was also true that Dean and Cas hadn't touched each other in years.

So Dean answered, even as he loathed the tone in his own voice, "I'm sure your followers would be happy for your attentions," and tried not to think of all the men and women Cas had been with in his desperate quest to remember what it was like before Dean took everything from him.

Cas replied matter-of-factly, "I don't want to spend my last night tricking damaged souls into letting me use them."

"You didn't mind doing that on your second to last night. Or the night before-"

"I am well aware of how far I have fallen, Dean," Cas said in a low voice, his anger flashing just enough to remind Dean that even a much frailer Cas was still willing to tell the camp leader had to show some respect. But Cas sighed then and added, "You see me for what I am. And you are right to despise me for it."

"I don't de-"

"And I despise you. I hate you. For everything. A hundred reasons, most of them fair. But I want to spend my last night with you anyway."

Dean looked suspicious. "You want me to pretend to be him? To be past-me?" he asked, voice cracking.

"No," Cas said, "Do you want me to pretend to be past-me?"

Dean was puzzled by the question. It had been so long since he had Cas had been with each other, long before Cas became the kind of man who used hardship and lies as tools for seduction. It was back when the angelic voices left a cold gap inside of Cas, and Dean would have done just about anything to comfort him.

And Dean surprised himself by answering, "Yes."

And Cas walked right up to him, got into his face, eye to eye, and said in a slow growl of a voice that Dean hadn't heard in ages, "We're doing this, Dean."

But it was just a parody of a being who used to be there. Dean went to turn away, but Cas grabbed his arm and pulled him back, with more force than he had ever seen Cas use on a non-infected human.

"This isn't happening, Cas."

"Because you think it'll be too hard to let me die if you actually feel something for me again? Because you stopped letting yourself feel any-"

"I don't need this shit from you tonight!"

"In case you hadn't noticed, Dean, I'm not here for your needs, I'm here for mine!"

Dean was startled. Because even after all these years, even after being human for so long, Cas didn't ever act like this before.

But he continued, pressing on, still right up in Dean's face, "Dean. I have never asked you for much. I gave up my power for you. I gave up everything for you. And now I'm willing to die so you can make an unwise and unlikely attempt to make up for all the things you've done to this world. And if I want to spend my last night taking advantage of the miniature sensations of this horrible human body, then that's what I'm going to do."

Dean was almost frightened by the way Cas was talking, by the fierceness of his glare and the cold lowness of his voice. But Dean felt something else when Cas added, almost tearfully, "I have never asked you for anything, Dean. Give me this. Even after... what I've become... I still deserve this from you."

Dean let out a quick breath. He was surprised, at himself as much as at Castiel. Because after all this time, after all Dean had become, it was still possible ask Dean something he couldn't say no to.

Dean nodded then, slightly, and moved his hand onto the back of Cas' neck, and was struck by how small Cas was, how fragile he was now. Truth be told, Dean still hadn't really adjusted to that fact. He leaned over to Cas' mouth and kissed him on the lips, long and slow, trying to make it sweet and gentle and almost-chaste.

But Cas just pulled his face an inch back and said, "We really don't have time to mess around, Dean."

And Dean realized then that Cas really wasn't trying to recapture the past, that perhaps this wasn't brought on by past-Dean at all. Cas wanted him. The fucked up version. The one who shared with Cas the knowledge that this was all their fault, the one who had seen enough horror to scrape his psyche clean of hope and other shiny things.

Cas didn't want nostalgia.

He didn't want to remember anything at all.

Dean threw Cas on the ground, and landed on top of him, arms supporting him so his full weight wouldn't crush Cas' weaker body. Cas looked up at him, eyes grateful and relieved even as his mouth looked like it was tasting something bitter.

But soon Dean's tongue was in that mouth, his left hand grabbing onto Cas' hair and his right gripping Cas' hip hard enough to leave marks. Cas closed his eyes and seemed to think of elsewhere, and Dean paused to ask "You okay? Cas?"

"Don't stop," Cas said, more a plea than an order.

Dean pulled up at Cas' shirt then, almost ripping it as it came off. He moved his mouth down to Cas' jaw and then his neck, and then used his teeth to scrape down the center of his chest, eliciting a sound from Cas' lips that was sweeter than anything Dean had heard in a long time.

Dean continued down to Cas' stomach as Cas lay there, eyes closed, savoring the sensations, when suddenly Cas decided he wanted more. He sat up and pressed his hands up Dean's shirt, thumbs holding tight enough to bruise. He looked into Dean's eyes, a quiet challenge, a demand. Make me forget. Make me forget everything.

Dean pulled Cas up by the elbow then and shoved him against the wall. He pressed his thigh between Cas' knees and let his hip press into Cas' groin a little harder than he needed to. Cas was breathing hard as he grabbed Dean's belt to undo the buckle. Dean threw Cas' hands back up and then held them against the wall, above Cas' head, as he bit down hard against Cas' shoulder.

As Cas grunted, Dean moved one hand down to undo Cas' pants button, and the loose fitting attire slid down easily. Cas quickly stepped out of them, and used his now-freed hand to grab Dean's jaw roughly and pull him up for another kiss, and the kiss was angry but needy, a jab and an apology all in one. Dean lifted Cas up higher and used his own weight to keep Cas off the ground and at an angle against the wall. They used their lips and teeth and fingers and when Dean entered him finally, pressing into him slowly but forcefully, Cas looked right at Dean, his large eyes letting Dean inside of him as much as his body was. Letting Dean see everything in him: the pain of Dean moving in long thrusts inside of him, more frantic and agressive than he was used to; the despair and loss and guilt he felt like sand scraping him raw from the inside; the swirl of betrayal and abandonment he felt toward his own kind; and the confusion - the puzzlement - the horrible nightmarish child-like sensation of not understanding, of never really getting why he felt pain or fear, of never really comprehending how any of this could really be happening, how he could be ever made too human and small to help the earth, how the entire earth could come so close to being obliterated. Dean could see it in his eyes then, little flashes between arousal and pain: that confusion that had been Cas' default expression when he first talked with an all-too-human Dean. Cas was still - despite all his apparent adaptation - so very confused about humanity. About everything. And Cas would do anything to find a decent way to make the confusion end.

Make it stop, was the silent plea, and Dean felt wetness falling from his eyes as he thrust harder and harder into Cas, as he pushed deeper into the only person left who knew him, the one who had seen his soul and knew what horrible things it had done and still thought it worth saving. The one who remembered the Dean that he no longer had the courage to be. And he would have done anything for Cas at that moment.

And as Cas brought himself to climax the tightening pressure around Dean made him come as well, and he let out a groan as he finally broke eye contact and buried his face into Cas' shoulder. He gently pulled out, causing Cas to wince slightly, and set him down but continued to lean over him, running his hand up and down Cas' cheek and neck again and again.

Dean wanted to express something - some kindness or a good bye or at the very least a 'Wow' at that intense last act. But when Dean opened his mouth, it didn't come out that way. Instead, his voice broke as he said "I should have done so much better for you, Cas. I shouldn't have let you become what you are now. I owed you better than that."

Cas just smiled sadly, eyelids heavy, and said, "Back at you."