Author's Note:

Alright. So, this thing snowballed tremendously. It was originally one of those one-sentence-per-word prompt things, but obviously that did not go as planned. Inspiration struck and I got the urge to have Dean be concerned about Cas becoming Endverse!Cas in the present, because I had a lot of fucking feelings about that and it never got resolved in canon. Yeah. Hopefully this is somewhat entertaining.

"No," Dean muttered as he shoved his way through the swamp of people. "No, no, oh hell no."

Sam trailed behind his brother, confused. "Dean," he called over the booming music, "why are you freaking out?"

Dean spun around quickly, but he didn't even look at Sam, his eyes still darting wildly around the room. "Cas," he answered in a clipped tone. "It's Cas – I haven't seen him since we got here."

Sam quirked an amused eyebrow. "You act like he doesn't disappear on us everywhere we go..."

"Don't be a smartass, Sam," Dean growled. "This shouldn't even be called a party; it's more like a damn rave. That means drugs and he could be getting into anything and–" He paused as Sam gave him a disbelieving look, then admitted, "I'm just... worried, is all."

Sam resisted the urge to slow-clap it out at Dean's confession. Instead, he rolled his eyes and teased, "This, coming from you – the king of hustling pool and drinking games – is priceless. Actually, your concern is sweet."

Dean didn't even deny his hypocrisy, just glared. "Well, excuse the hell out of me for not wanting to see Cas higher than a kite again."

It took Sam a minute, during which they searched through more of the large crowd for Cas, before Dean's words fully sunk in.

"Wait, wait, wait," Sam said concernedly, grabbing Dean by the shoulder to stop him. "What do you mean 'again'? There was a first time?"

"Son of a bitch," Dean groaned. "I need to stop letting things like that slip."

"Dean," Sam said sternly, "explain."

Dean sighed, hand combing through his hair. "It hasn't even happened. Not yet, anyway, and I don't plan to let it."

Sam nodded slowly. "Okay, so, time travel."

"Yeah."

"And when was this, exactly?"

Dean glowered at the wall. "Apocalypse of '09. After you took off on your own, that douchey feather-duster Zachariah sent me five years into the future, when the Croatoan virus was in full swing. Long story short: you wore dear old Luci to the prom and the Cas in that universe was human, like he is now. He was also a hippie-slash-druggy who hosted orgies and, let me tell you, the guy popped pills like a champ. Chuck was there, too. Told me to hoard toilet paper."

Sam blinked. "Um, okay. Wow. My brain froze at 'orgies'."

"Oh yeah," Dean said flatly, "it was a real adventure, Sammy. Future-me was a militaristic asshat and everything."

Sam snorted, recognizing the subtle jab towards their father, then he scrunched his nose as something occurred to him. "Wait, five years from 2009... Dean, it's 2015 now. In other words: six years from your experience, not five. Isn't it safe to say that that's not going to happen to Cas?"

Dean frowned, shaking his head. "Not taking that chance, Sam. He's human right now, and you didn't see how bad he–"

"Hello, Dean."

Dean nearly jumped out of his skin when Cas latched onto his arm. "Fuck, Cas! Make some more noise, will ya?"

Sam almost snickered at the double-meaning to his brother's words as he thought about what other context they could be used in.

Cas actually did snicker, leaning heavily into the eldest Winchester's side, which seemed to deeply disturb Dean. Sam could kind of understand; it wasn't like Cas laughed that often, or was physically affectionate in any way, shape, or form unless he was freakishly happy to see them. And after the conversation they'd just been having...

"So, Cas, what've you been up to tonight?" Sam started before Dean could grill their friend with harsher, far less subtle questions. "Did you find anything on the case?"

"Not exactly," Cas answered. "I've just been-"

Cas broke off with a yawn and shifted his arm so that it was slung over Dean's shoulders, then laid his head on the shoulder nearest to him with his eyes closed. He seemed to have forgotten they were having a conversation entirely. Dean looked caught between pushing Cas off of him or relaxing into his hold. The latter won out, at last, and Sam couldn't contain a small smile.

But then Dean had to ruin such a perfect moment by clearing his throat awkwardly. Cas jolted as though he'd been zapped, blinking rapidly in confusion at his surroundings before the movement turned sluggish with sleep once more.

"What were you doing this whole time, Cas?" Dean repeated Sam's question.

"Umm..." Cas hummed lowly. "Socializing, I suppose. I got quite a lot of free drinks from the people that I conversed with, but I didn't stay in their company long, even when they, apparently, really wanted me to."

Dean's jaw flexed as he clenched his teeth, a telltale sign of his growing irritation. He then gave Sam a look that the younger Winchester wasn't sure how to interpret. Dean shrugged Cas' arm off and began pushing him out of the building, Sam following silently behind them, still trying to piece together whatever Dean had figured out that he hadn't. His brother had always been more familiar with this type of scene.

"De-ean, wait." Cas turned lazily on his heel and decided to drape himself over Dean again. Dean paid no mind to it, only grabbed the intoxicated man's limbs and dragged him forward. Cas squeezed his arms tighter around him. "Dean, where are we going?"

"There's nothing for us here," Dean explained, and hey, technically it was true even if it wasn't his ultimate reason for wanting to leave. "It's a cold trail, none of us have found anything connected to the case all night."

"Okay," Cas mumbled into his ear. "Just don't put me down. You're warm. Warm is nice."

"Whatever, Cas." Dean sighed, refusing to acknowledge how hot his face felt as he pushed open the wooden double-doors.

The two brothers and their accomplice quickly found the Impala, Dean fishing his keys out of his pocket. He unlocked his Baby and opened the backseat doors to nudge Cas through them. Cas, however, wasn't having it, and he roughly yanked Dean into the backseat with him. Dean let out a startled yell as he and Cas knocked knees and elbows and heads, but the blue-eyed idiot was laughing and it was nearly impossible to stay mad.

Dean still managed, though, grumbling under his breath. "I guess you're driving," he grumpily told Sam, and very reluctantly tossed him the keys.

Sam tried not to join Cas in laughter - really, he tried so goddamn hard - but Dean was pouting.

"Yeah, yeah," Dean snapped. "Just keep laughing and we'll see what kinds of viruses I can get on your laptop."

Sam's laughter promptly shriveled up and died in his throat, right as the Impala roared to life. Cas' laughter silenced itself, too, but only because he'd fallen asleep, sprawled lengthwise on the seat with his head awkwardly tucked against Dean's side and not quite in his lap.

"What even happened to him?" Sam asked. "You seemed like you knew."

Dean didn't acknowledge him, and Sam was about to get angry – he'd lost track of how many times Dean had ignored his questions throughout the night – until he caught Dean raising a hand in the rear-view mirror. Cas had slumped further, cheek now pressed to Dean's thigh. His brother's fingers twitched above Cas' head, as though they wanted to run themselves through Cas' hair, but Dean just curled the hand into a fist and let it drop. Sam couldn't resist rolling his eyes this time; Dean really needed to stop kidding himself.

"Do I need to repeat–"

"People being scumbags, Sam," Dean said quickly. "That's what happened."

Sam clenched his jaw against his brother's vagueness. "Still not following."

"Typical party stuff, Sam!" Dean hissed, then rolled his eyes. "Oh, right, how could I forget? You never went to parties; you stayed home and got your nerd on, dated your textbooks instead of that hotty in your math class."

Sam gave him the bitch-face. "Seriously, Dean? Are you going to start this again?"

"No," Dean huffed. "Because even you should know what roofies are."

The younger Winchester's eyebrows raised in surprise. "Wait... someone roofied Cas? In all honesty, I thought that was a tactic used strictly on girls."

Dean narrowed his eyes, subconsciously pulling Cas closer as he cocked his head in a 'really?' motion. "That's what you're going with, Sam? Used strictly on girls?" he questioned severely.

"Wow, okay. Hearing it again, I sound like an ass," Sam conceded with a grimace.

"Yeah, you do, but I think that's kinda normal for you," Dean agreed distractedly, looking at Cas.

"How do you think he even stayed awake if he got roofied? He should have been out cold a lot sooner."

"Probably lingering angel side-effects, man." Dean shrugged, looking out the windshield as the Impala arrived at the bunker. "Go ahead, Sammy. I'll get Mr. Comatose up and follow in a minute."

Sam craned his neck to look back at Dean. "You sure you can get him out by yourself?"

Dean nodded. "Yeah, 'course I can."

The Impala's door slammed shut behind Sam, and Dean switched his gaze to the ex-angel lying across his lap, shaking him as he whispered, "Hey. Wake up, Cas."

Cas' brow furrowed as he stirred awake. "Wha–" his words broke with a tremendous yawn before he could continue, "Dean? What is it?"

"Come on," Dean prompted, bouncing a leg under Cas' head to get Cas off his lap and out of the car. "We're home, buddy."

"Oh, I see. The bunker," Cas murmured sleepily. The sharp movement against his head was doing absolutely nothing to motivate him. He couldn't just abandon the little warmth he still had, and he was already going limp again, eyes shutting. Dean was here, after all – and to Castiel, Dean meant safety.

But the hunter in question groaned and sat up more as Cas sank back into his lap. "No, Cas. You can relax again when we get inside."

"No," the other refused shortly.

Dean huffed in disbelief and tried to push Cas off of him again, alarmed to feel a rumble come from the unwilling lump. Dean froze. Cas was growling at him.

"No," Cas stubbornly repeated, fingers grabbing onto the fabric of Dean's shirt.

Dean sighed. "Why're you doin' this, Cas?" he asked wearily, almost sure that there was some reasoning behind this stubbornness.

Cas shifted and mumbled something unintelligibly against Dean's stomach.

"What was that?" Dean tried to clarify, trying not to shiver at the feel of hot breath fanning over his stomach through his shirt.

Cas lifted his head slightly to say, "You are going to leave when we go back inside. You always do." He let his head drop again and Dean felt a tug as Cas' grip on his shirt tightened. "And I... I don't want you to this time. I want to stay like this."

"Cas..." Dean breathed, feeling his heart melt a little at the kicked-puppy look Cas was giving him. He sighed once more; damn those eyes. "Look," he began, and his tone made Cas look up in interest. "How's about – ah, once we get inside, that is. Seriously, man, forget doing anything in here because you drool like a friggin' llama, and my room is a lot more– I mean–" Dean faltered slightly at the quirked eyebrow Cas sent his way, but he forged on; it was now or never. "Sleep with me, Cas?"

There. It was out in the open, plain and simple, but Dean was blushing like hell, not to mention flipping the fuck out on the inside. He could swear he'd never been more terrified of hearing any answer in his life, which was really saying something considering his line of work and the kinds of questions he had to ask on a regular basis. Cas' stunned silence and wide-eyed gaze was more than a little off-putting. But then, just like that, Cas' demeanor changed from stunned to... panicked?

"I am not sure we are on the same page, Dean. I only wished to spend some more time with you, not... not engage in any type of– um, well, I suppose that's not entirely true. I suppose I had just expected you to ask... later?" Cas' eyes wandered nervously about the Impala. Dean was left feeling more confused than ever at yet another sudden shift in behavior.

"Wait, Cas, what the hell're you talking–" and then it hit him like a ton of bricks. He thinks I mean sex. "Holy shit! Cas, no. I didn't mean 'sleep with me', I meant sleep with me. As in slide into bed next to me and sleep. Not any of– of that."

At least not yet, his mind slyly added, and Dean almost smacked himself for allowing it. Then again, Cas had implied that he wasn't entirely opposed to– NO, Dean stopped that train of thought once again. Dammit, he needed to get a grip.

"Oh," Cas blinked and the apprehension was gone. "In that case, of course."

Dean was more than happy to let it go, too, shoving at Cas' back again. "C'mon, then, out we go."

"There seems to be a problem with that plan, Dean," Cas stated flatly. "I don't... think I can move on my own."

The hunter shook his head in exasperation but pulled the Impala's handle and popped the door open nonetheless. He shimmied out from under Cas, only to basically fall out of the car. Dean recovered quickly, though, and hooked his arms underneath Cas', dragging him through the opening. "Jesus, Cas," he groaned, "if this is what parties do to you, remind me to never let you within ten miles of one ever again."

"I'm sorry for the trouble," Cas apologized, limp as a noodle as his arms were left bent at an awkward angle. He could already feel himself beginning to slip out of Dean's grip and grimaced in discomfort. "I don't think this is a very efficient method, Dean."

"Well, shit..." Dean thought a moment before asking, "Think you can manage to get on my back?"

Sam nearly choked on his coffee when the bunker door shot open and slammed into the wall with a bang.

Dean paid him no mind as he practically sprinted through the door, Cas wide-eyed and clinging to his back like a koala to a tree. They made a bee-line for the hallway, both of them grunting and hollering various exaggerated things ("Dean! Dean, stop! Oh my father, we are going to die!" "No, this is how you live, Cas!") throughout their fast-paced struggle. Sam followed a minute later, once he'd let himself comprehend the whirlwind that just tore through the room. He raised his eyebrows at the conversation he picked up as he drew near Dean's closed bedroom door.

"I want the right side."

"No way, Cas, that side's mine. Always has been, always will be."

"But I'm your guest, Dean. Aren't you supposed to be hospitable towards guests?"

"You ain't no guest! You live here, in case that somehow slipped your mind."

"This room is still foreign to me, so technically I qualify as a guest here, if not anywhere else in the bunker."

"You're not stealin' my spot, Cas."

"I will admit that I typically take the left side, but I've decided to start expanding my horizons."

"Like hell you have! You've just decided to start being a little shit!"

"I will smother you with this blanket, Dean."

"See? This is the culture of little shits everywhere!"

"Oh, I'm sorry, would you rather I assault you with this pillow instead?"

"No, you damned dork."

"Dork? I'm not certain if I regret agreeing to this or not, since you seem to be determined to call me names all night."

"Yeah, yeah. Love you, too, babe, now get in."

And Sam could have sworn he actually heard Cas laugh.

"As you wish, Dean."

Sam rolled his eyes, shaking his head all the way back to his chair and slightly choked-on coffee. At least those two were finally getting a clue.