Author's Note:

So, last year, after Sacrifice aired, I wrote a little fic (well, 103k words, but who's counting) called You Fall In Flame that I ended up being very proud of, and it was very therapeutic for the time that nothing was on air. So, given some encouragement from the good people of Tumblr, I've decided to do it again this year.

YFIF was being largely influenced by the song Stars from the musical Les Miserables, and I thought it would be good to do the same this year. I've chosen the Imagine Dragons song Demons. I was going to use Monster, but I feel it applies more to Sam than it does to Dean, and Demons followed the theme I wanted to adhere to more closely.

So, without further ado, I present It's Dark Inside, a post-season 9 AU.

Chapter 1 - When The Days Are Cold

Sam was pacing the small room by the time Crowley actually showed up, looking very irritated.

"I was busy, Moose," he growled.

"Dean is dead," Sam snapped at him, his tone torn between anger and grief. "This is your fault; you're the one who convinced him to use the damn thing."

"I know he's dead," Crowley informed him, rolling his eyes. "What do you think I was busy with?"

Sam's focus moved instantly to Crowley's eyes, searching for answers. "What does that mean? What did you do?"

Crowley shrugged. "I didn't have to do anything. I was merely exploring a theory. Are we done here?"

"No, we're not done here!" Sam told him incredulously. "What the hell are you talking about?"

Crowley raised an eyebrow at him. "I've always preferred to show than tell, personally." With that, he vanished.

Sam allowed his irritation with Crowley to drift away as he started to grow more and more concerned about what the demon might have meant. Suddenly worried that something might have happened to his brother's body, Sam bolted out of the room and down the hall, eager to reach Dean's bedroom and make sure nothing was amiss.

Whatever Sam had been expecting, seeing Dean sitting upright in bed with an expression of bewilderment wasn't it. Before Sam could even voice his surprise, however, he lost all his words at the sight of Dean's eyes.

Black. Flat black. Demon black.

"Sam?" Dean's gruff voice sounded like he'd been gargling gravel, but he didn't sound nearly concerned enough for the situation, so maybe he just hadn't noticed yet.

Sam realized he was frozen in the doorway so he forced himself into the room. "Oh my god, Dean, are you okay?" It felt like a stupid thing to ask, but Sam was feeling a little out of his depth at the moment.

"I feel groggy," Dean admitted, "and a little achy, but otherwise I feel a lot better then I did this morning. What happened?"

"Uh..." Sam trailed off, not sure what to do. Half of him wanted to hug Dean, thrilled that somehow he was alive, but the rest of him was too freaked out by the eyes to think straight.

Dean's eyes narrowed as he examined Sam. "What happened?" He asked again, more insistent. "You're worrying me, here."

"What's the last thing you remember?" Sam finally asked. It seemed like a safe enough question.

Dean's brow furrowed with concentration. "I'm not sure." He held up a finger to stop Sam from commenting. "Give me a sec." After a pause, he nodded slowly and winced. "I knocked you out and went after Metatron."

Sam scowled at him briefly. "Yeah, you did. Is that the last thing you remember? Nothing after you left to go find Metatron?"

"I don't think so. Flashes of fighting him, maybe, but that's pretty much it. What happened, man? You look really freaked." Dean peered at him, another expression that was tainted by the black eyes.

"Dean...Metatron stabbed you in the chest," Sam told him gently, watching his newly resurrected brother warily. It probably said something disturbing about their lives that he wasn't more freaked out about the resurrection part.

Dean's hand flew to his chest, only to find no wound. "And yet I'm sitting here talking to you with baby smooth skin, so what aren't you telling me?"

Breathing out tiredly, Sam stepped back and indicated the mirror on Dean's dresser with his finger. "Until like ten minutes ago, I thought you were dead. There's something you need to see, and it's probably going to be a pretty big clue in the whole coming back to life thing."

Warily, Dean stood and moved towards the mirror. He slowly picked it up and stared at his reflection. There was a very brief moment where Sam thought his brother wouldn't react, then the mirror slipped from his fingers and clattered noisily on the ground, the metal backing preventing it from shattering.

Sam moved forward as soon as he realized Dean had stopped breathing, tugging his brother back towards the bed and snapping his fingers in front of the jet black eyes a few times. "Dean, hey, Dean! Snap out of it!"

Sucking in a deep breath, Dean shook his head violently, shoving away from Sam and stalking towards the wall. "No, stay away from me. What the hell happened to me, Sam? Why the hell are my eyes black?"

Sam shrugged helplessly. "I have no idea. Crowley might, though. When I summoned him, he told me he already knew you were dead and gave me some enigmatic crap about 'exploring an idea,' then he took off again. I was worried, so I came back here, and you were sitting upright and breathing. I'd barely even had time to process that you were dead again." He paused, then admitted, "I might be in shock."

"What the hell were you doing summoning Crowley?" Dean demanded.

"What do you think I was doing?" Sam asked him, irritated. "It's his fault you had the damn mark and blade in the first place, and I was going to make him do something about it."

Dean's eyes flashed back to normally almost instantly, and his expression became mildly confused. "What happened to you not saving me?" He questioned.

Sam was looking at the door, and he shook his head. "That's not what I said, Dean. I never said I wouldn't try to save you, I said-" He cut off, glancing back to see Dean's eyes were back to normal. "Dude, they're normal again!"

Distracted, Dean moved forward to snatch the mirror off the floor, double checking. "Oh thank God," he breathed. "Am I okay then?"

"Not the person to ask," Sam reminded him. "We need to find your demon boyfriend again."

Dean scowled at him. "Not funny."

"Hey, I don't have to burn your body tonight," Sam reminded him. "Let me celebrate how I want."

Dean rolled his eyes. "Finish your sentence," he insisted.

"What sentence?" Sam sighed.

"What did you say? Cause I heard pretty loud and clear that you wouldn't have tried to save me." Dean folded his arms and looked at his younger brother expectantly.

"You said that if the roles had been reversed, that I would have done the same thing," Sam reminded him. "I wouldn't have. Not even close. That doesn't mean I wouldn't have fought like hell and done whatever I could've to save your life, but I would never have brought you back against your will by tricking you into accepting possession, Dean. That's what I said. When I told you before that we could be partners, but brothers was a whole different issue? That wasn't because I stopped caring about you." Sam rolled his eyes, like it was a stupid notion to even suggest. "You're always going to be my brother, and I'm always going to have your back, but that doesn't mean I didn't come out of the whole Gadreel incident with some serious trust issues, man." Sam breathed out and ran a hand through his hair, suddenly looking a lot more tired than he had a few moments earlier.

Dean nodded slowly, following Sam's train of thought, and wincing slightly at the reminder of the lie he'd told to save his brother's life. "I'm sorry I lied to you," he offered. "I can't be sorry I saved your life though."

"I can live with that," Sam shrugged. "It's a start, at least. We'll fix everything one problem at a time."

"How heart warming," Crowley griped from the doorway, startling both brothers. "I thought I'd have gotten a phone call by now, but no, Moose and Squirrel need to have a heart to heart first." He rolled his eyes and made a tsking noise.

Dean's eyes immediately flashed flat black again, and his pose became defensive. "What the hell is going on, Crowley?"

Sam started when he saw Dean's eyes shift back, and he turned to Crowley for answers. "You know what's going on with him, don't you? Why he's alive and why his eyes look like that?"

"It isn't just his eyes," Crowley scoffed. "Big bad hunter Dean Winchester is officially a demon. Full blooded, real deal." He tucked his hands in his pockets and shrugged.

Dean stared at him for a moment, too in shock to really process that revelation. "No way," he finally insisted. "No way in Hell!"

"Funny you should phrase it that way," Crowley smirked.

"Shut up, Crowley," Sam shot at him. "Dean, calm down."

"What the hell do you mean calm down?" Dean whirled on him, furious. "My eyes aren't just black, Sam, I'm a demon! What happens now?"

"We find a way to fix it," Sam said firmly.

"You can't," Crowley said, his tone bored.

Sam scowled at him. "Why the hell not?"

"Because now that he's a demon, the mark isn't going to kill him if he decided not to go on a killing spree," Crowley pointed out, exasperated. "Cain lived for years without touching the blade, remember? He's a decent chap, too, little overbearing perhaps, but then, you were never the cuddly type to begin with."

Dean moaned and sat down heavily on the bed next to Sam. "My head hurts," he muttered.

"The mark was going to kill you?" Sam asked softly.

"Mmmm," Dean murmured noncommittally. "I found out before I went after Metatron. Not killing made me feel like I was dying. Eventually I would have. Crowley said something about Cain being a demon making him strong enough not to kill, I guess."

"Yes, standing right here," Crowley reminded them. "You'll be fine. Might need a bit of training in using your demon skills, but hey, that's why you've got me on a speed dial."

Sam raised an eyebrow at the newly restored king of hell. "What aren't you telling us?"

"Lots of things," Crowley acknowledged. "Dean really will be fine though, that's true. Less dark-side than he was before, if you can believe that. This transformation isn't going to automatically make him the physical embodiment of evil, and the mark is going to affect him a lot less. There's a learning curve, and I'm not planning to run out on him, so really, this shouldn't be very concerning."

Dean raised his head to squint at Crowley, eyes still black. "Why do you care?" He asked, perplexed.

"Because for some bizarre reason I actually like you two morons, and Moose over here gave me enough human insight to force me to care about your well being." Crowley huffed and rolled his eyes again. "I'm not exactly happy about it, but I'm invested in your health and well being."

"That's so weird," Sam muttered, shaking his head.

"I'm the one who has to keep their affinity for the two most notorious hunters in the continental United States under wraps or risk losing a kingdom," Crowley snarked at him.

Dean raised his head and smirked. "Only the continental US? What, are there some epic badasses in Alaska or Hawaii we don't know about?"

Crowley sighed and turned away. "I don't know why I bother." With that, he vanished.

"I need beer," Dean announced, standing and striding towards the door. "C'mon."

"Why?" Sam asked, curious as he followed his brother out of the room.

"Because I don't actually need it," Dean admitted, his black eyes shifting, "and I'm curious if I can make myself need it if I drink enough."

"That sounds healthy," Sam muttered.

"Does alcohol kill demons?" Dean shot back at him.

Sam shook his head. "Not that I know of, and let's give it a day or so before we start casually joking about this, okay? I plan to do a hell of a lot of research into how to manage this new version of you."

"I figured we'd just have you cure me," Dean said, surprised. "Since, you know, we can do that now?"

Sam moved forward and tapped the mark on Dean's arm as he passed him into the kitchen. "Can't. Apparently, being a demon is going to let you stay alive without turning into a mass murderer. If that's how it has to be, we're going to know as much about how to handle this as possible."

Dean's eyes snapped back to green, reflecting his disappointment. "So this is really me now?" He asked quietly.

"Hey," Sam said, catching his attention. "There's a lot we're going to have to learn. But for right now? You seem pretty normal to me. We'll figure out all the hell stuff later."

"Together," Dean emphasized, relaxing as Sam nodded his agreement.