Summary: It's a split second choice - probably the only one they have left. But Dean makes it, because it's Cas lying there, bound and beaten, with a bomb strapped to his chest counting down all their deaths. How bad could it be, saying yes to an angel? Season 12 AU

A/N: So sorry for dropping this story for almost a year. I didn't want to post any new chapters until I had this story fully completely (so I could post once a week with no more of this ridiculous delay) and it seriously took me the last of this year to actually do that. But huzzah! The story is now complete and I will finish posting over the next month :D

Thanks for everyone who favorited/followed and those of you who've come back despite the delay! You are all the best :)

-o-o-o-o-o-o-o-o-

Cohabitation

Chapter 3

-o-o-o-o-o-o-o-o-

Letting Cas rest until he was recovered enough to give them some state of where they stood took about a week. The first days were the worst. With Dean sleeping on and off about twelve hours total a day and eating three times the food a normal adult male might consume in one meal, tension and worry ran high. Even Dean started getting twitchy and defensive, taking most of his growing concern out on Sam, since he was the most convenient (and only) target.

So when Dean woke up after his more usual four hours on the fourth day and didn't eat the daily contents of an average American four-person household, the two brothers let out a collective breath they'd held since the barn and started breathing easier.

Tensions were still up, particularly anytime Dean caught Sam researching angelic vessels (which was most of his spare time) or when Sam brought the topic up. Dean seemed to be going for gold in the sport of avoidance and denial. Sam wasn't sure if it was all that previous guilt finally built into a wall of pure stupidity and stubbornness, or if something more was going on. But his brother was adamant about baring Cas's grace like a cross on his back.

Sam tried to bring it up several more times, but Dean shut him down each time, insistent that there was nothing they could do until Cas woke up, so would he just drop it.

"I don't get it, Dean," Sam countered during one such discussion after a week of discussions. They stood in the kitchen on perhaps the first day Dean hadn't tried to eat them out of house and home. "You can't just pretend this isn't happening."

"Of course it's happening, Sam. I'm the one with the angel in my head!"

The younger Winchester threw out his arms. "That's exactly my point!"

"What point?" Dean was almost yelling across the kitchen island, sandwich forgotten on the plate in front of him. "All I keep hearing is how you can't leave Cas be. The guy almost died!"

Sam pinched the bridge of his nose. They seemed to only be talking in circles and it was getting old. "This isn't about him. It's about you."

Dean pulled his head back, staring at his brother with a furled brow. "What?"

The brunette let out a sigh and pulled out one of the stools to slide his large frame down onto. He locked eyes with his brother, trying to put his sincerity and concern in his expression so that Dean, for once, wouldn't jump on his words with the defensiveness of a mama bear.

"You've got an angel riding shotgun. Right now, it's an unconscious angel, so you haven't had to share the wheel. But when he wakes up, you two are going to have to learn to live together."

Dean fidgeted under his brother's watchful gaze, and ended up rolling his shoulders defensively. "So what. We've all been under the same roof for years now. What's the big deal?"

"What's the-" Sam huffed in disbelief and shook his head. His brother was being purposefully obtuse; Dean wasn't that stupid. "Sharing living space and sharing head space aren't exactly the same, Dean! You're forgetting that I know what that's like."

"You're comparing Cas to Lucifer?"

"No," Sam replied through clenched teeth. He took a deep breath, reminding himself that when his brother felt cornered he usually attacked by shifting blame. "I'm actually talking about Gadreel. Lucifer isn't the only angel I've served vessel to, you know."

The blonde snapped his mouth shut at that and ducked his gaze, cheeks tinting red. He had been directly responsible for that fiasco, after all, and Sam hadn't pulled punches mentioning it. They had put it behind them over the years, but that didn't lessen the fact it had happened.

"What's your point?" Dean muttered, still not looking at him.

"My point is, you're the biggest control freak I know." His older brother's head snapped up at that, and Sam shrugged. The truth hurt, but right now it wasn't the hunter he was worried about. "You don't like people driving your car, Dean. We're talking about another person driving your body. Yeah, you saved Cas's life, but what kind of life is it going to be if he never has the reigns? If he can't talk, can't go where he wants or do what he wants?"

Dean swallowed, finally realizing what his brother had been on about all this time. Sam hadn't been talking about kicking Cas out. He'd been talking about rescuing him. From Dean. Stubbornly, the hunter rallied a defensive, weak as it was. "It's not a prison sentence, Sam."

"Not an intentional one. But if he can't get himself out and we can't find another vessel, you're going to have to learn how to share your body, your mind, with another person." That wasn't even bringing up the fact that his brother was also the most emotionally constipated person he knew. Dean not having a place to hide all of that pain he refused to let anyone see was going to kill him.

Dean didn't respond, staring down at his sandwich in distaste. Sam climbed off the stool, pushing it in against the counter.

"Cas deserves more than riding shotgun," he said softly, remembering how hard a time their angel had been having these last few years. He'd struggled with his mortality, humanity, and then his broken grace once more. Sam could still hear Castiel referring to his own resurrection as a punishment like it was yesterday. They'd been getting better these past few months, all three of them. They'd been working on it, but that didn't erase the past or past insecurities.

They couldn't let this become just another fate for the angel. Their friend deserved more. With that soft reminder, he left his brother to his meal, though he had a feeling Dean didn't have much of an appetite anymore.

-o-o-o-

Since that confrontation, Dean put more effort into helping his brother research. Not much, mind you. He'd never been very good at hitting the books, even when he was committed to it and not sulking like a scolded school boy. Still, Sam took what he could get.

It was several days later that Cas finally resurfaced. They were in the library, stacks of books and notes spread between them. Dean had been on the same page long enough for Sam to know he wasn't really reading it. Suddenly he straightened up, pulling his feet off the desk and setting the book off to the side distractedly.

"Cas?"

Sam looked up, eyes wide and brow raised. Dean's eyes flickered back and forth as one often does talking to someone they can't see. Sam set his pen down on top of his notes as he watched his brother anxiously listen to a conversation he could only hear one side of.

"Man, it's good to hear your voice." Dean's face broke into a smile and he sent a relieved nod in Sam's direction. "Welcome back, buddy. You had us worried."

Not privy to the angel's response, Sam gestured at his brother, who only shrugged with a wide eyed expression. It wasn't like he could put it on speaker. He relayed the information Cas was telling him, confirming that he was going to be alright, but he was still weak and would be for some time.

"Are there any reverse effects for Dean?" Sam asked as Dean paused in his dictation. His brother shot him a warning look, but Sam countered it with a bitchface of his own. "If there are any, we need to know now rather than later."

Judging by Dean's pissy expression, he figured Cas agreed with the younger over the older.

"No, he doesn't think so," Dean replied with no small amount of grump in his voice. "Any damage he may have caused would have healed this last week. I told you Sam, I feel fine."

Sam ignored his brother, instead directing his questions at the other occupant of the room. "And you're okay, Cas? I know it was kinda hairy there for a minute."

"Yes, he's fine. No, the situation was hairy, not you- what? That doesn't even make sense, why would Sam be asking that?"

Following the one-sided conversation was like watching a tennis match against a wall, and Sam snorted. Cas must be alright if he was back to misunderstanding colloquialisms and calling them out. The younger Winchester considered telling his brother he could talk to Cas in his own head, he didn't have to speak out loud. But then he'd be sitting in a silent room with no access to the angel. Plus, he spent enough time prying information from his tight-lipped brother as it was. No way he was intentionally closing this avenue before he absolutely had to or Dean figured it out on his own.

"He says he's fine," Dean clarified, the sarcasm in the almost formal comment coming out clear. "There, happy? No, I'm not saying that."

Sam arched a brow.

Dean made a face, ducking his head like a child forced to talk to his schoolyard crush. "He says he's 'touched' by your concern." There was silence for a beat before the older hunter rolled his eyes and added, "and he's glad we're both in one piece."

Sam quirked a half smile at his brother's brooding and embarrassment. "That doesn't sound like Cas."

His brother glared at him. "I paraphrased."

Sam laughed, finally breathing freely after a week of damn depressing tension.

"Cas, now that you're awake, we should talk options." Despite the grin stretched across his face, Sam switched topics back to the less ideal task of figuring out their next step. He didn't know how long Cas would stay awake for, and he had just about reached the end of what he could do without the angel's help and input. He pulled up his notes and the information he'd gathered on vessels and alternatives.

"Sam-" Dean was shooting him another warning look, but whatever he was going to say ended as he furled his brow, listening to the angel in his head. His brow lowered in a deadpan expression of pissed off huffiness, but he relayed the words all the same. "He says that's a good idea."

The brunette sent a smug look across the table and Dean bristled. But Sam quickly launched into the research. The first thing they'd need to establish was whether or not Cas would be able to leave his current vessel, or if he'd need assistance.

"He just woke up, dude. Cool it." The rebuke was followed almost immediately by, "Damn it, Cas, I'm not kicking you out and you're not a burden."

Given he was only audience to half of the conversation, Sam could only guess at Cas's side of it. After all these years, though, he knew the angel well and wasn't surprised in the slightest that Castiel's thoughts were aligned with his own.

Dean was still ranting with his angel, who was apparently grateful for the manner of the save, but disliked that it meant inconveniencing his friend. Sam listened to his brother bounce between flustered and embarrassed, and angry and defensive. It was adorable, in the younger Winchester's opinion (it was about time the two of them had a conversation not derailed by emotional constipation), but it wasn't exactly getting them anywhere, either.

"Let's focus on our options for now, and you two can go back to trading 'No, after you's when we figure out our next step." Dean shot him another look, but Sam just raised his eyebrows and dared his brother to tell him he was wrong. "Cas, can you leave voluntarily?"

The blonde broke off his heated glare as the angel answered internally. His face fell minutely, but immediately tightened in resolve. So that was a no, and Guilty Dean was picking up the slack faster than it was actual existing.

"Stop apologizing, Cas, it's fine," Dean said flippantly, even as he shook his head in his brother's direction.

"Okay, we figured that would be the case. What about Dean rescinding his permission. If you're not strong enough to leave, would that help, or would it do more harm than good?"

By the way Dean's eyes widened half a minute later and he adamantly and harshly rejected the idea, Sam figured Cas's answer was the shy and hesitant version of 'I should say no but I'm as big a martyr as either of you, and as it's not technically impossible it is therefore a yes in my self-sacrificing brain.'

Dean's firm 'No' was the shorter version.

"You know, you could let Cas have this conversation," Sam mentioned casually as his brother shook off whatever the angel had said or not said.

Dean immediately looked affronted. "It's not like I'm keeping Cas from talking!"

The hunter froze immediately at the thought and panic flashed across his face even as his gaze slid down and out of focus, which Sam was starting to identify as him talking or listening to the angel. "I'm not, am I?"

There was nothing but silence for Sam. Dean eventually flushed a bit in his cheeks and suddenly looked away from his brother: the patented guilty look for the older Winchester.

"Dean?"

His brother chewed on the inside of his cheek, guilt turning into sullenness. So, Dean had been wrong and someone else right. Sam didn't exactly need three guesses to who that could be. "He says he wouldn't do that to me. Wouldn't 'force another's will' on me."

Yeah, not like Sam hadn't seen that one coming, having figured as much back on day one. Dean, on the other hand, was starting to think his brother might have had a point about rescuing Cas from the unintentional prison he and the angel had created in an effort to save his life.

"It's not like that, Cas," Sam rallied with a soft smile, deciding to save the 'told you so' for another time. Dean had enough on his hands, especially since he was only just realizing it. "It wouldn't be by force."

"Hear that?" Dean threw the question into the quiet room, but judging by the lack of shift in his expression, it was silence he got back internally too. He shrugged a minute later when it was still clearly a no-go.

"Alright," Sam shrugged as well. They'd have to do this by patsy. "So unfortunately I could only find one method of removing an angel from a vessel involuntarily."

He was, of course, talking of the grace extraction device he and Cas had previously tested on the residual power residing in him from Gadreel. In truth, Sam had found a second option: rumors of exorcising an angel. Unfortunately, it hadn't panned out. He'd never been able to find the source, only rumors, and he'd wasted days looking for it before finally calling it as information lost over the ages.

It hadn't been easy to let go of it, either. Sam really didn't want the Men of Letter's grace extractor to be their only option. His tone was as hesitant as the rest of him, remembering the agony that experience had been. He didn't want to put either of his brothers through that unless they had no other choice.

Given Dean's confused look was quickly turning stormy, Cas had either filled him in or was pleading the fifth. Sam had a guess as to which one was more likely.

"We can wait until you're stronger, of course," the resident bookworm added with a weak smile. He had no intention of using that thing until he was sure both Cas and Dean were strong enough to take it. "But we should figure out the plan now so we can be ready."

Because there was no telling how long the two could actually survive with one another, especially with Cas stubbornly refusing to assert any control and Dean spiraling into a guilt-laden abyss. Oh yeah, it was going to be a fun couple of weeks while they got this sorted.

"Where are we even gonna find another vessel?" Dean broke in, staring at his brother questioningly. "We gonna trick some other sucker into being possessed?"

Given the way his face darkened and he followed his own statement up with, "Sarcasm, Cas," the angel wasn't a big fan of that option either.

"I've been doing some digging, and I think I may have found a way around it." Sam sorted through the books around him until he found the one he was looking for and handed it to Dean, who raised his brow at the title.

"Golems?"

"Yeah, they're creatures brought to life by magic, usually sculpted from clay-"

"I remember," his brother grumbled, thoughts drifting to the giant of a man who had nearly killed him back in their Nazi fighting days.

"It's the only solution I've found that doesn't sacrifice someone else as a vessel. Golems are empty; they don't have souls." Sam shrugged one shoulder. "Otherwise, we can try to resurrect Cas's body. Maybe Crowley could do something?"

Dean shook his head, and Sam could almost swear he was shaking it for both of them. "Cas says not to involve that douche if we can help it, and I agree."

Which Sam had also figured. It wasn't his first choice either.

"He says he's not sure if he could inhabit a golem for the same reason angels can't possess corpses." Dean leaned back in the chair, translating the information to his own speech pattern as Castiel spoke within him. "Souls act as a buffer between angel and body, so the vessel doesn't burn out. And an angel requires something to grant permission. A golem might not have either problem, cuz they're tough as hell and the spell could work as permission. But he's not sure how to change the spellwork to incorporate his grace as the power source instead of the creator's will."

It was fascinating listening to the mix of his brother and Castiel's voices as one. Not that Cas was speaking; it was definitely his brother dictating. But Dean slipped in and out of Castiel's more formal and informed speech patterns as he relayed the information, half paraphrased and half repeated.

"Great, that's not a no, so I'll take it." Sam passed Dean several sheets of paper, some copied from spell books and others hand written in a speedy scrawl. "I've looked into the spell and possibly altering it. I think it's doable. I'll need your help with it, Cas, but I didn't see any big obstacles there."

Dean read through the papers, lips mouthing the words quietly, though Sam knew Castiel would be able to see through Dean's eyes to read it for himself. His brother wasn't as good at spellwork as Sam was, so he didn't expect Dean to be the one to spot any problems. The blonde was far better at sigils and warding than Sam would ever be, but witchcraft had taken a bit more readily than Sam was actually comfortable admitting. Of course, it had gotten them out of their fair share of issues, so he wouldn't argue with it, either.

After a moment, Dean sat back and nodded, rubbing at his eyes. "Cas says it might work."

Sam broke out in a smile, the first real good news he'd felt since climbing out of the Impala that night, watching smoke billow into the air with both his brothers beside him, alive. "It'll take some more research, but it's a first step."

-o-o-o-

Dean left Sam to his books and his notes. The sasquatch didn't even notice him scoop up his coffee cup and leave the Library, too busy scrawling notes and edits on spellwork for creating a Golem with renewed fervor now that they had a game plan. Dean mentioned getting something together for dinner as he left, but he doubt his brother even heard him.

He entered the solitude of the kitchen with a deep breath, the silence comforting and overwhelming all at the same time. He tossed his cup beside the sink, the clatter breaking up the empty room.

Now that he was alone, he braced himself against the counter, fingers curling around the edge of the sink, and closed his eyes.

"Cas?"

It was weird, he could admit, having another presence in his head. Cas was keeping pretty quiet, but Dean could still feel him. Whether that was out of that misguided feeling of being a burden or because he was still tired and healing, the hunter wasn't sure. Probably both, knowing their angel. But he knew, even with the silence in his head, that Cas was still there. It presented almost like a gut instinct in the middle of a hunt; he could feel the angel, sense him just on the periphery. Whether it was fleeting emotions, swells of thought that he was pretty sure weren't his, or the comforting warmth in his chest that had to be the angel.

Well, that, or an oncoming heart attack. He'd certainly eaten his fair share of cheeseburgers in his lifetime.

"I'm here, Dean."

The hunter let out a slow breath and opened his eyes. Straightening, he made for the fridge. Speaking of heart attacks; he'd told Sam he'd be cooking up dinner and he had every intention of doing so, even if the guise of it had really been an excuse to speak to Cas in private. Dean moved on autopilot as he pulled out a couple of steaks and some of Sam's rabbit food.

"How are you feeling – really?"

"I'm very tired." The honest reply came after only a second of hesitation. Dean knew Cas had considered telling him he was fine, and not because he was in the guy's head as much as Cas was in his, but because he just knew the angel that well.

He sounded tired, too. Cas had put on a brave front while talking to Sam earlier, not that the younger Winchester could see or hear him. But he'd done so regardless, and Dean hadn't bothered mentioning it to Sam. Kind of a low blow to call the angel out on something he couldn't hide from the guy serving as his vessel.

"Yeah, I figured. Well, rest up and take all the time you need, buddy." Dean pulled out a skillet and cutting board. He flipped on the stove and starting chopping up the greens.

"Thank you for offering yourself to save me, Dean. Surrendering your body is a sacrifice I can never begin to repay, and I-"

"Whoa, Cas, enough," Dean cut the angel off, knife stilling against the board. He fought the blush rising to his cheeks and instead focused on not taking a finger off with how tense he suddenly was. "It's no biggie, alright?"

Unless Sam was right, he thought absently and with a little more bitterness than he ever would have let Cas hear. Then I'm apparently serving as your own personal prison, and that would be a biggie, damn it.

He almost sliced the tip of his pointer clear off (thank god for fingernails), his muscles suddenly even more tense, before Dean realized it wasn't him doing it. It took another moment to realize why Cas was tensing them up, and he choked on the sudden lump in his throat that tasted a lot like dread.

"You heard that, didn't you?" Dean tipped his head back with a defeated sigh and let the knife clatter atop the cutting board. "You can hear all my thoughts."

It wasn't a question, and Cas didn't answer it – not directly. But the guilty silence and flood of discomfort was telling enough. Dean lowered his head back down, chin damn near his chest, as he breathed in deep.

God damn it, Sam hadn't just been right, he'd been very right. Dean hadn't thought this through. How the hell was he going to live with Cas in his head, hearing his every thought? He wasn't a nice person in his head. Hell, he wasn't even a good person, and his only saving grace was that he usually kept most of that shit to himself, unless he was drunk. Or angry.

"You are a good person, Dean," Cas insisted, though considering the source material he was answering had been an unspoken thought Dean would have never let him hear aloud, the angel wasn't really helping either of their cases. "I am sorry for this situation. I promise, with Sam's help, we will remedy it as soon as possible-"

"It's fine, Cas," Dean answered by rote, wincing when they both realized how untrue it was at the same time. He groaned aloud, since it was pointless not to. "Okay, so fine isn't exactly the right word but… It's better than you being dead."

And that was the truth. Cas could read his friggin' head if he doubted it. Not that the angel did, from the swell of warmth and devotion that felt a hell of a lot like love that Dean got in response.

"We'll work it out, alright? And until then…" Dean shrugged, picking the knife back up. "I don't know. We'll figure it out, I guess."

"We will do what we always do; get through it together." That time Cas sounded a little more like himself and Dean chuckled at how literal it would be this time. The tension eased, and the hunter and angel went back to making dinner.