As Dean pressed him against his living room wall, Cas remembered what he had to do and quickly pushed him off.
"Wait."
He needed to take the potion. He couldn't do this, he couldn't have Dean if he hadn't already sipped the drink that would turn him back.
He already knew he wouldn't be strong enough afterwards.
Dean was selfish. He knew that very well. And so, when he understood what Cas was about to do, he turned away. He was pretty sure he couldn't have watched him drink the damn thing. Worst case scenario, he'd try to wrestle it out of his hands.
The red liquid didn't taste like anything, and yet Cas shuddered as it ran down his throat.
He'd done it. This was it. In twelve hours, this would be over. Irreversibly so.
He threw the glass away; he could hear it shatter somewhere in the room, but didn't pay any attention to where it had landed as he pulled Dean back into his arms, all thoughts of why this was a bad idea long gone.
They kissed desperately, drowning in the feeling of finally being as close to one another as they had desired, taking a few short deep breaths when necessary.
His fingers worked their way under Dean's shirt, relishing in his warmth. Dean's mouth moved down, worshipping his neck. He groaned.
Had intimacy always felt like this? He couldn't remember. It had been so long.
It didn't matter.
He reluctantly brought some distance between them to pull Dean's shirt over his head; he immediately went to return the favour and spent a few moments grumbling about "these damn buttons" before continuing to nibble on his neck. Cas unexpectedly turned them around so that it was Dean pressed against the wall and he could explore his chest as he wished.
"Cas..." he mumbled breathlessly, clawing at his naked back.
"Come back up here – " he managed. They kissed again, and Cas, being tired of waiting, started to drag him towards his bedroom –
"Caveman" Dean murmured against his skin, biting slightly down.
"Same" Cas forced out.
They reached the bed that he hadn't shared with anyone for longer than he could remember; but then they fell in, and he forgot that he had ever been older as he was now, that there had been a time when he hadn't known Dean Winchester.
As his hands danced across Dean's skin, as he kissed him deeply, all he knew was Dean Winchester.
Dean kissed down his chest until Cas pulled him back up to devour his mouth.
They had not pulled the curtains shut and for a short moment in between, Cas stopped moving and just admired Dean's beauty. He answered with a playful grin and another nib at his neck.
He would have marks all over his body when they were done.
Cas relished the thought and tried to repay the favour.
Now and then, they pulled away slightly, barely touching, calming down so they could start over, their fingers itching to learn more, their breathing ragged, until they couldn't bear it anymore and moved close again, neither of them able to say who broke first.
Finally reaching completion, Cas couldn't say whether he was screaming or not, but either way, it didn't matter, he was overwhelmed, he was being dragged along mercilessly, and Dean was right there with him.
Afterwards, they curled into one another until it was difficult to distinguish whose limbs belonged to whom.
Cas thought that he had never been happier than in this very moment.
Soon enough, they were both fast asleep.
When they woke up they didn't speak for a while, both content to just lie in one another's arms and forget about the rest of the world.
Dean was the first to get up, happily pronouncing "Lunch!"
They were both aware that they were play-acting, pretending. Somehow the closeness they had shared had given way to a lie they were both desperate to uphold, if only for the hours that remained. For that time, Cas was just that – Castiel, called to the bedside of Dean's dying neighbour; and Dean was the helpful new friend who'd offered a hand immediately. And the one thing had led to another.
Perhaps, Cas thought, they should talk to one another. Clear the air.
But what was there to clear? Just a thing; a tiny thing neither of them had mentioned.
It was clear they would miss one another. It was clear they would have wished things to continue as they wear.
But neither of them had talked about love.
And it was this that he was feeling, lying here, listening to Dean move around as if he belonged in his house, his life. Love like he had never felt before.
Did Dean feel the same? Maybe. Probably. Hopefully –
No.
Not hopefully.
How much longer could Cas have? Certainly his heart would give out one of these days. Knowing this, the memories he had of Dean, brief as their time truly together had been, would bring more comfort than pain.
But Dean... He was still so young, and he felt so strongly. His emotions, despite his reluctance to talk about them, often showed openly on his face.
He didn't want him to hurt because of him, but if the way Dean had held unto him in the afterglow was any indication, that was exactly what would happen.
And yet he couldn't even regret it. How could he possibly have brought himself to? Dean was so bright, so beautiful; anyone would be drawn to him, and to have the luck to be have one's interest reciprocated –
Lost in his thoughts, he hadn't noticed Dean climbing back into bed with him. He only became aware of his presence when warm arms wrapped themselves around him and kisses were pressed against the love bites Dean had left there.
"Lunch's ready" he muttered. "We could stay here though..."
Cas laughed, and to his own surprise, it actually sounded happy and carefree.
"I think we both need some nourishment."
Dean's stomach growled. He stopped kissing Cas and sighed.
"Suppose you're right". He grinned. "Still a damn shame, admit it".
Cas playfully shoved him off the bed.
Dean was determined that this wouldn't turn into a cry fest. They might only have a few hours together, but by God Cas was hot and he was going to enjoy every last minute. Beside, this was his style, wasn't it? Live in the moment, make quick decisions and then live with the consequences? The patented Dean Winchester guide to living, so why should it bother him at all?
It shouldn't. So being happy it was.
"I hope you like spaghetti Bolognese by the way, it was all you'd got left in the kitchen – and I had to search for that."
"I do" Cas assure him as he pulled on boxers and an old t-shirt. He followed Dean in the kitchen, where the plates were already set out. He'd really miss Dean's cooking; it was always delicious; but he carefully avoided mentioning it lest Dean should offer to come over even more often to look after him.
While he would be happy if they were still friends after –
The point was, he didn't want Dean to assume the role of nurse. After this, it would feel wrong. Humiliating, even. Cas knew that Dean would never see it that way, but it didn't make it any less true.
After they had eaten, Dean stood up and reached out for him.
A few minutes later, they were back in the bedroom, getting lost in each other all over again.
Later, when they woke up after another nap, Cas glanced at his watch to see that six hours of the twelve he had left had already past.
The clock seemed to move faster with every passing second. Cas had believed that he had got used to the minutes ticking by more and more quickly through the years, but it had never felt as fast as this.
Cas wanted Dean to leave before... before. It was one thing if he should return to find Cas old again, but to force him to watch it happen...
Somehow, Dean seemed to guess. An hour before the time ran out, he let go. They had been what Dean refused to call "cuddling" on the sofa.
Dean seemed about to say something, but decided against it. Instead, he only shook his head and bent down to press a last, gentle kiss against his lips. They stayed like this, their foreheads pressed together, for several heartbeats before the young man abruptly stood up and left without a word.
Dean cursed himself for being a coward the second the door closed behind him, but he couldn't possibly have said what he'd felt at that moment. Cas was doing the right thing – he wouldn't have been Cas if he hadn't – and the last thing he needed to hear was how ridiculously cut up Dean was about this whole thing when he had no business to be.
Plus, the sex had been awesome, and he was no stranger to one night stands. So really, this was that.
Only it wasn't.
But that was his problem. He'd deal.
He always did.
This time, Cas knew exactly what was going on when he began to feel weak and sick and tired. As before, he saw no point on returning to bed. He might as well wake up to his old life where he left it only a few short days ago.
It felt like it had been years.
The last thing on his mind as his consciousness faded was Dean, no one but Dean, and how the time they had been given had not been enough, since a whole life would not have been sufficient to let him know how much he'd come to mean to him.
He woke up, his back protesting against the way he'd contorted his body as he'd slumped down on the couch. He kept his eyes closed, just breathing, remembering.
Dean in the car, their hearts still beating wildly from their encounter with the Old Man and his gang.
"Can I kiss you?"
Dean making him breakfast and lunch, his strong hands carefully preparing the food he insisted he needed...
Dean, smiling, laughing, in his arms –
Dean –
It hurt more than he had expected it would. He finally forced himself to get up, but refused to look at the mirror or even down at himself. Not yet. Not while he could still taste Dean.
It had begun to snow, he noticed.
And soon enough, he heard the tell-tale sound of a shovel being scraped along the pavement, perhaps with more force than strictly necessary.
Dean.
Of course he would still clear his drive, even after... everything.
He yearned to throw open his front door and pull him into his arms, but that was no longer possible. Even if Dean would be willing to –
No. It would be wrong to bind him to someone who had so little life left in him.
He wondered if Dean would come in for his usual cup of tea, if they could save at least a sliver of what their friendship had been.
He put the kettle on without looking down at his hands. He didn't want to see the old man's hands he had slowly grown accustomed to in the last twenty years, knowing they would disgust him.
When there was a tentative knock on his door, he went to open it with a wildly beating heart.
Dean stood there, looking at his feet, shovel in hand.
"It started snowing again" he told the ground.
"I saw" Cas said, causing Dean to look up. His mouth fell open.
"Dean?" he asked as the shovel clattered down.
"Cas" he inquired, "have you looked into a mirror at all in the last few hours."
"No. Why – "
His body understood before his mind did and he hurried to look in his bathroom mirror.
He didn't look a day older than thirty-one.