AN: So I received this prompt on Tumblr from wwtgrace13:
"How about writing an AU where Sam, Dean, and Castiel are mutants and they have to fight against the bad mutants (demons, shifters, vamps, etc.) and anti-mutant people. Just thought it would be something."

This really grabbed my attention because - as some of you may know! - I really love superpowers AUs (for example my spn/tdkr crossover 'Hellfire' and the Sherlock fanfic series staring with 'A Study In Silver'). Plus, I am a MASSIVE fans of the X-Men films and comics (in case you were wondering, that's the type of mutants we're dealing with here).

This is set around season 4, and will be a massively AU version of that season. All will be explained throughout the story - but if you have any pressing questions, feel free to ask!

Let me know if you enjoy this :)

"I can't tell for sure, but I think there's just the one shifter out there. Loads of human perps though,"
"Why do bad things happen to good people?" Dean groaned quietly from their position in the storage cupboard, just off the large main lobby of the bank.
"I think the case here is more like 'why do bad things happen to you'," Sam countered.
"Shut up. I'm a good person,"
"Whatever, man," Sam teased.
"Can we just get this over with?" Dean asked irritably, eyeing a mop critically in the light from the keyhole.
"I think what Dean suggests is wise," Cas put in hastily.
"That's a first – ow! That was my foot!" Sam hissed.
"Quit bitchin'. I'm going after the shifter," Dean declared.
"How do you know which one it is?" Sam asked warily, and even in the poor light, Dean could sense his impatient eye roll.

Sam and Cas checked their ammunition in the meagre light, each carrying a shotgun, with two pistols in holsters in addition. Dean didn't tend to carry things that reacted poorly at high temperatures. He had a knife, though, as always.

"I'm sure I'll be able to tell," Dean replied condescendingly.
"Oh I'm sorry, I didn't realise you were the one out of the three of us that can sense when people are lying," Came the snarky reply from his brother.
"No, you're right, I'm not, but I am the one in full control of my powers,"
"Dean!" The elder Winchester winced slightly, as both his comrades told him off at once.
". . . I believe we should attack now before we are discovered," Cas decided.
"Yeah, yeah. Whatever, feathers," Dean muttered before they made their move.

They burst out of the closet at once, making short work of the journey to the main lobby, and catching the bank robbers by surprise.

Sam and Cas fired quickly and efficiently at their enemies, while Dean merely set a few of them on fire with a wink. They were immediately met with return gunfire from several of the bank robbers, though – the ones who identified themselves as such, anyway. It was common for robbers to hire shapeshifters to kill and replace bank staff or customers, so that if someone decided to break in and take them on, they could pretend to be a civilian until the last possible moment. By then, for the would-be rescuer, it was too late.

It was expensive, though. This robbery was fairly small-scale; they'd only hired one shifter to pretend to be a hostage that Sam could make out.

The three of them headed for separate corners of the room, ducking for cover and eyeing everyone – robbers and civilians alike – with suspicion. There were a few large plant pots and decorative marble blocks to hide behind. As previously agreed, they'd split up: more targets meant their enemies had to split their attention.

However, when Cas and Sam arrived in their separate hiding places after dodging haphazard gunfire, they didn't find them uninhabited: only Dean, whose giant plant pot was slightly too close the bank robbers' position for comfort, found his position empty.

In Cas' corner, behind a marble block, a wounded man who'd been shot in the gut earlier for protesting against the hostage situation was experiencing his death throes, with only another hostage – an employee of the bank with a dislocated shoulder who had no idea what to do – as his companion.
"I – I didn't know what to – oh God, help him, please-" She was babbling. Cas ignored her.

He looked down at the severely injured man blankly from where he was kneeling, and saw the complete desperation in his eyes.
"Please," He begged softly, though even he didn't know what he was asking for: life, death – just no more pain, Cas presumed. He could do that.

He took the man's shaking hand, and pressed two fingers against his forehead with his free hand.
"Sleep now," He told the wounded man, whom he had healed in the blink of an eye. The man fell into unconsciousness on command.

Sam, meanwhile, was communicating with another injured hostage behind a marble block parallel to Cas'.
"Stay calm, help's on the way," He murmured to the woman, who was bleeding from the chest. He supposed the jagged glass sticking out from her skin was planted there by the hostage-takers, using charges to get through the bullet-proof glass of the bank-tellers' positions. Glancing over at Cas, he confirmed that he'd be able to come and help this woman in a minute.
"Can you tell me where the other hostages are?" He whispered. There were very few hostages in this room: mainly dead or dying, they couldn't have been the entire contents of the bank when the criminals took control.
"S-s . . ."
"Shh, it's okay. Don't talk," Sam replied, once he had established that yes, there were more civilians, and yes, she knew where they were. He put his hand to her head and looked into her eyes.

It was fucking difficult to read her: she was panicking like crazy, and his adrenaline was working against him so that he was mentally straining to even hear whispers of the thoughts in her mind. Luckily, she was still considering his question, so it only took him about ten seconds to get the answer out of her. Just as well, as he heard footsteps approaching his hiding place.
"The safe. Thank you, ma'am,"

She looked up at him in fear, even thought she was in tremendous pain. He wished he had time to explain that she was wrong about which side he was on.

Cas looked up. One hostage-taker was approaching the area where Sam was trying to read a hostage. He looked back at the woman with the dislocated shoulder. He expected her to stare at his with awe, or disgust, or even hatred. He was surprised when instead of doing so, she balked. She looked him in the eye for a second, before losing her nerve. She suddenly wrenched her own arm downwards, relocating the shoulder, and shot up, running for the doors.

Gotcha, Sam thought, as the woman bolted across the room. The shifter would know that going up against three mutants wasn't worth the risk: she was cutting her losses.

Aside from the one approaching him, Sam knew that the human bank robbers were all either smouldering on the floor after being burned by Dean, bleeding from gunshot wounds inflicted by himself or Cas, or hiding waiting for the three of them to come out into the open so that they could shoot them.

From his hiding place, Sam looked at Dean, and mouthed, Stay here. Cover me. Hostages in safe.
Dean's shocked and indignant face was confirmation that he understood – they'd perfected lip reading a long while ago.

The very second he had a clean shot on the man approaching him, he unloaded his gun into the man's knee, sending him screaming to the floor. In the resulting confusion and panic, the other criminals began to panic, firing wildly: in the midst of this, Sam shot up, running as fast as he could after the shifter.
"Sam!" Dean cried, though he knew his warning was futile: his brother wasn't going to stop now. Gunfire followed Sam as he rushed stealthily across the large room, following the shifter. Dean did his best to ignite those who were aiming at his brother, but it was hard when he couldn't see them properly from his position.

Fuck it. He stood up, throwing his arms out towards the men and praying they weren't near anything flammable – or worse, explosive. In the ensuing firefight, Sam got away, leaving Dean and Cas to incapacitate the human criminals. It was over before it even began: when Dean started throwing fireballs, they fled as quickly as they could, though they didn't get far; some even dropped to their knees in surrender.

"Please – we'll cut you in, man-" One of them begged at Dean's feet. Dean rolled his eyes.
"Yeah, yeah – whatever. Is it true? Are there hostages in the safe?" He demanded.
"Y-yeah," Another of the cowardly thieves confirmed. "But wait, like – you can't want to save these people? They hate you! They hate you, and what you do, and what you are-"

He was promptly cut off by Cas touching his head. He fell to the ground, out cold.
"See if there's anyone else in here that needs healing. I'm going after Sammy," Dean commanded, and Cas frowned, but nodded once.

As an afterthought, Dean paused before he left, addressing the criminals again: "-oh, and when he gets there, they'd better be alive. If not – well, we'll be back for you," He threatened, glaring at each of the remaining men in turn.
Dean dashed off, trying to figure out which direction the shifter and his brother had gone in. If they'd gone down into the sewers, the way the three of them had arrived (it was the only foolishly unguarded area of the bank), he'd struggle to find them quickly.

At the same time, Sam chased the shifter into the basement: he thought that he had backed her into a corner. He took his gun from its holster, and cocked it, ready to shoot her when the moment arose. Silver bullets would be necessary for this one – shifters, with their own very radical branch of the mutant genome, had developed their own set of vulnerabilities different to those of most other mutants. Silver was one of them.

The basement contained the grating they'd arrived through to get into the bank in the first place: Sam spotted the shifter about to exit through it and yelled, "Freeze!"

The shifter did, indeed, freeze. It turned around. Slowly.
"Well, looks like ya got me," She said, raising an eyebrow.
"Yeah. Looks like I did," Sam replied, keeping a careful watch over her.
"What kind of mutant betrays another mutant like this?" She sneered, her emphasis on the word 'mutant' implying that she thought very little of him.
"One like me," He replied simply.
"And you are?" She asked, putting her hands on her hips. When he didn't answer, she sighed, "Come on. It's not like I'm getting out of here,"
After a long pause for thought, Sam saw no flaws in her reasoning, and gave in: "They call us the Men of Letters,"

She actually laughed. "This ain't the comic books, kid. It's dumb to have a name like that – if you're a known group of mutants with a name and matching uniforms-"
"We don't have matching-"
"-people will think you're terrorists," She continued, ignoring his protest. "They'll pin this whole thing on you, y'know – the robbery, the death of civilians. Of the poor little bank teller," She pointed to herself and grinned maliciously.
"We'll see," He grunted, keeping a steady aim on her. He didn't want to act until Dean arrived. Shifters were slippery, and he didn't want her to get away.
" . . . Yeah. Guess we will . . . But as it happens, I have heard of you,"
"That so?" Sam asked conversationally, not really caring about the answer – or, at least, trying not to care.
"Oh, yeah. There's the fire one–" She tutted, shaking her head, "Very bad temper, I've heard," Sam smirked. She didn't know what she was talking about, "I heard he burnt down his house as a kid. Killed his own mother,"
"That's not true," Sam corrected. He was trying to remain calm, but he couldn't let that one slide. Where was she getting this information from? The true parts, anyway?

"Oh, yes. Then the one who thinks he's – I don't know, he's a healer? Super religious, though. A man of God. Strange, though, that God would curse him to be a mutant in the first place. Guy's a bunch of contradictions," She carried on, adding the last part in a stage-whisper that made Sam sneer – he didn't like people mocking Cas as much as he didn't like people mocking Dean. They were both family to him.

"That's enough," Sam growled, trying to get her to stop. But she continued anyway, of course.
"Then there's the freak," Sam's heart felt cold, as her words sounded like a gong, resonating with certain memories of his father of all people. Freak.
"Yeah, even for a mutant, you're something, aren't you, Sammy Winchester?" She asked with a mocking expression.

Sam frowned – how had she known his name?

". . . A psychic, whose powers are somewhat iffy if I'm not mistaken. Visions here, some crappy telepathy there – then the accidental powers, the uncontrollable telekinesis. I've heard he can make you do things, just by telling you to,"
"Shut up," He spat. His gun was shaking slightly in his grip.
"Unstable, by all accounts – a hair's breadth from going completely Rogue,"
"I am not like them!" He yelled at her, stepping closer in the midst of his fury.

And that moment was all it took.

From the back of her trousers, hidden under the back of her blouse, she whipped out a small gun, which she quickly fired into his face. He barely had a second to think and panic before it had happened.

"Sammy!" Echoed a voice somewhere in the distance, along with a grittier call of "Sam!"
This was it. This was how he was going to die. There was complete silence after the deafening bang of the gun firing.

The first thing Sam noticed in the silence was that he was still alive. And that he had shut his eyes.

He opened his eyes, gazing forward, trying to figure out exactly how he'd survived. He saw the bullet literally centimetres from his face, and gulped. The look on the shifter's face was priceless.
"Not so crappy after all, huh?" He asked her breathlessly, picking the bullet out of the air and holding it in dumb surprise. The shifter took that moment to make a dive for the grating hole, but was met with a silver bullet from Cas' gun to the shoulder, which caused it to yowl in pain. It already had an injury there.

"Come on, we'd better drop her off at the station . . ." Sam began, turning around to face Dean and Cas. They were both staring at him with fuming and surprised faces, respectively. He floundered for something to say for a moment.
The best his brain could come up with was, "Uh . . . Ta-da?"

"Ta-da?!" Dean asked, dumping his bag of supplies he'd needed for the raid down on the table, the flame-retardant material making a rustling noise as it hit the mahogany surface. "Ta-fucking-da, Sam?"

Sam, who like the rest of the team had maintained an awkward silence throughout the journey home in the Impala, knew that his brother had wanted to wait til they got home to have this debate. Somewhere with sprinklers and fire extinguishers. And that place was their grandfather's bunker.

They'd come into possession of it after the fire at Sam's apartment in Stanford. It was lucky, really, the timing – but then again, with their grandfather being an expert on mutants and the supernatural, and knowing a time-travelling mutant, what else could they expect?

He'd just turned up out of the blue one day, approaching them to tell them the story of how he came to be there: he was part of a secret society that were researching theories of mutation, and possible links with the supernatural. Another member of the society, a time-traveller called Gabe, had informed him that his grandsons were mutants. Delighted, he decided to give them the keys to the society's bunker, in order to join them.

Figuring he'd just given them a place to live at best – and that he was an utter crackpot at worst – they went to the bunker once he'd gone back to his own time, expecting to find loads of 'Men of Letters' as the society was called. But when they found none, they decided to stay anyway. They had no home, except their car, having moved around a lot during their childhood so that their father could attend his precious anti-mutant rallies.

They never did find out why there were no Men of Letters left. However, with a vast, uninhabited and well-furnished bunker up for grabs, the brothers decided to use the place as a headquarters for their work against the vitriol that their father, and people like him, had spread for so long. Saving people, hunting Rogues – the family business. Well, it was now that their father was gone.

"I don't-" Sam began, already knowing it was kind of useless to try and put his point across right now.
"Damn right you don't! You could've been killed, Sam!" Dean roared, placing his palms flat on the table.
"But I wasn't!" Sam protested, rolling his eyes and raising his voice slightly to compete with his brother's. He gripped the back of a chair tightly from the other side of the table, staring at his brother and Cas, who was awkwardly staring at the floor, awaiting some unspoken permission to leave.

"You didn't know you were gonna survive though, huh? You looked damn surprised at your amazing little trick, just like the rest of us!" Dean countered. Sam noticed him remove his hands from the table, conscious of heating up and leaving black burn marks on it, just like every other time he got angry enough. There were enough blackened handprints on the thing already.
"Well yeah, I was surprised! Strangely enough, I've never stopped a bullet at point blank range before, Dean!" Sam replied sarcastically, a sardonic smile gracing his features and infuriating his brother further. His fingers tightened their grip on the chair.
"You've also never successfully used your telekinesis on a case before, either. What were you thinking?!" Dean asked, only half-wanting an answer.
"I didn't mean to do it! I didn't see she had a gun, alright?" His younger brother tried to reason.
"Which is why you should always wait for me! Don't even get me started on the fact that you ran away, leaving a total shit-storm for me and Cas to clean up alone,"

Cas shifted a bit at that, watching as Dean waved his arms angrily in his direction. He wished he'd had the foresight to leave earlier, when it would have been deemed socially acceptable.

"She would've gotten away, Dean! What was I supposed to do, let her?! She was a Rogue! You know, the same type of mutant that killed our whole family, that made us unable to tell anyone who we are, what we are, cause they'll think we're fucking terrorists?!"

"Sam," Cas interrupted suddenly, aware of how Dean was about to react to Sam dragging up their painful past, and not wishing to get a face full of fire tonight. He drew the attention of the two brothers easily, their heads turning towards him from their respective sides of the table that stood in the centre of the war room. ". . . What changed?"
"What?" The Winchesters both snapped with the same tense expressions.

"You used your telekinesis. What facilitated that?" He tried to put it gently, but he knew it was pretty much a lost cause by now. Anything he said was going to cause tension when the brothers were in a mood like this with each other. Sure, by tomorrow they'd be receptive to his thoughts – but today, they were at loggerheads with each other, and the world. He should have left this until tomorrow.

"Well, uh . . ." Sam thought about it for a moment, ". . . I was gonna die?" He answered, voice laced with sarcasm once more.
"Survival instinct. Go on," Cas replied, and Sam wasn't sure he'd understood that he was being gently mocked. He tried again, thinking more seriously this time:
"Um, leading up to her getting the gun, she was – uh, she was saying some pretty horrible stuff. About you guys . . . About me," He finished quietly, clearing his throat. Cas had a sinking feeling he knew Dean would share when he heard his next words:
"And you were angry?"
". . . Yeah," Sam answered, the realisation of what Cas was getting at slowly dawning on him.

The room fell into a long silence. Cas and Dean shared a meaningful look that made Sam sick to look at.

"Sammy, you gotta get your powers under control," Dean muttered after a little while.
"What? You think I'm a freak, too? Just like she did?" Sam asked quietly. Before Dean could deny it, he changed the subject with a shake of his head: "She knew things about us, Dean. Stuff we haven't told anyone outside this room. Our real names, how Mom died – kind of,"
"That's aside from the point, Sam. You gotta practise more," Dean persevered.
"I practise too much, Dean," Sam argued. "The more I use them, the . . . The more powerful I feel. Like I'm capable of anything, and that . . . That's not a positive feeling. I know it isn't. But I can't help it, every single time I go to read someone's mind; every time I fall asleep and see the future, I just feel . . . Unstoppable. And it shouldn't feel good, but it does," He finished, finally finding the words he'd been struggling to say to Dean all these years about how alien, how strange his powers felt when he used them. Almost sinister.

". . . Sammy, just – please, don't go unstable on me. I don't know what I'd do if you – if you-"
"Went Rogue?" Sam finished, his eyes blazing with hurt. "Jeez, Dean, I didn't know you had such a low opinion of me," He paused, looking down for a moment at his reflection in the mahogany.
"I'm not stupid, Dean. I know what's best for me. I know what I'm doing," He asserted.
". . . Do you?" Dean asked.

There was another long, hostile silence. Sam stared at Dean, his eyes dark. He shook his head, and turned away, storming off towards the staircase.

". . . I'll be in my room, in case you wanna check I haven't gone Rogue in the middle of the night or something," He shot back bitterly.

When he was gone, Dean sighed.
"I just – I don't know what to do, Cas. He needs to practise more, but the more powerful he gets the more unstable he is, and I just-" Dean's words trailed off, and he slumped down into one of the chairs stationed around the table. With a thought, he started a fire in the fireplace, and tried to relax. It was hard when he was so mad at Sammy, and at himself for not handling the situation as well as he could've. Cas stood next to him, staring into the fireplace looking pensive. Dean knew he was about to add in his two cents worth, but he didn't have the energy to stop him, and besides – perhaps Cas would have a better perspective on this whole mess.

"It was wrong of you to imply that he would join the very group you hunt every day. Rogue mutants are abominations, who have failed to appreciate the gift God has given them; they choose to commit sin with it," Cas pointed out, and Dean nodded. He strode up to the liquor cabinet and poured himself a drink, wishing he had some ice to cool it with. Maybe then he wouldn't feel so hot, too.

Cas continued as Dean sat back down, sipping his whiskey, "I do believe that your brother . . . He chooses to do good, with his gift. He chooses to channel this powerful feeling he gets into our cause; to use it for good,"
"For now," Dean muttered into his glass.
That caused Castiel to frown, looking down from where he stood at Dean's side. "You have never been a man of faith, Dean. But I always assumed you had more faith in your brother than this,"

Dean looked up, catching his friend's sympathetic but somehow still disappointed expression.
"Yeah, me too," The older Winchester replied, not breaking eye contact.

Castiel bowed his head, sighing at his friend's predicament.
"I will pray for your brother – I will also pray for you, Dean Winchester," He supplied, trying to be helpful.
"Whatever you say, feathers,"
"I would prefer if you refrained from calling me that," Cas huffed, pursing his lips.
"Why not? Is it blasphemous?" Dean asked, his voice a little tongue-in-cheek.
"It is rude to call an Angel of the Lord such names,"
"What makes you so sure you're an angel, anyhow?" Dean asked, slightly suspicious but more than anything simply interested. From the get-go, Cas had always told them that he didn't think he was a mutant: not really. He sincerely believed himself to be an Angel. And while Dean wasn't one for believing in that kind of crap, he decided to leave Cas alone about it for the most part.

"Because I have Grace running through my body, as blood runs through your veins," Castiel asserted, turning and following up the stairs Sam had gone up before.
"Blood," Dean laughed bitterly, "Y'know, after all these years, I could swear it's actually fire running through my veins by now,"
"That's the whiskey talking, I believe. Good night, Dean," Cas replied, shaking his head with a small smile as he left the room.
"Night, Cas,"

Dean was still there, dozing quietly in front of the embers of the fire, when Sam padded softly down the stairs on his way to the kitchen. He had been tossing and turning in bed for a few hours, but he couldn't stop worrying about the argument he'd had with Dean, and thinking that his brother was onto something. Needless to say, that wasn't conducive to sleep. Sam was a light sleeper anyway: he had been all throughout their childhood, what with all their father had told them about Rogue mutants sneaking into their room in the middle of the night and killing them in their sleep. The only time in his life he'd managed to sleep easy was when he was at Stanford . . . Jess would stroke his hair to calm him down; just the sound of her breathing, her heartbeat, and her warmth were enough to send him right off. It was simple things like that that he still missed, four years later.

Obviously, when she was taken from him, he'd reverted back to fitful sleep at night, woken up by the slightest of noises or barely-scary nightmares. The only time he truly slept well was when he was having a vision, and even then, it didn't feel like sleep. It was like being awake all the time.

He stopped when he reached the bottom step, seeing Dean's sleeping form slumped over in the chair, a whiskey glass hanging perilously from his slack hand. He shook his head, half in disapproval and half in amusement. Typical Dean. He's gonna make a great old man.

If we make it to that kind of age, he thought sullenly.

He felt bad about earlier, needless to say. He knew he'd been wrong to run off, leaving Dean to clean up his mess while he went off after the shifter alone. It was reckless, yeah, and he could've been killed if his survival instinct – or his anger, as Cas had helpfully pointed out – hadn't kicked in to save his ass at the last minute. But he had to catch her: he felt he owed it to the world to get rid of the Rogue mutant, seeing as he was coming so close to being one himself.

He shuddered, thinking of all the news reports he'd seen on them growing up as he walked to the kitchen for a glass of water. His father used to relish in turning up the volume, so he and Dean could hear all the awful things that tiny percentage of mutants had done. The kidnappers, the bank robbers, the sex offenders, the murderers, the terrorists. They gave mutants a bad name: ask any human out there what they thought of humans, and the likelihood they'd have a non-prejudiced opinion about them was slim to none. Dollars to donuts, they'd recoil in fear, disgust, or just pure hatred because the only mutants they'd ever heard about on the news were the Rogue ones.

Rogues: the ones who actively hated humans; who hurt everyone around them, and the ones they loved, simply because they couldn't control their powers. The ones with powers so unacceptable, so unstable, and so evil, that they were completely unable to be redeemed.

Past the point of redemption. If my powers grow any more, that'll be me. I can't become completely unstable. I can't let them grow into something that will make me like them. I can't risk the chance of hurting Dean, or Cas. Dean was right. I need to get this under control.

He returned to the war room, having poured the water basically on autopilot. He thought about going straight for the stairs, but then decided to wake Dean up so he could go to bed. He wouldn't be happy in the morning if he slept like that all night: he'd have a sore neck, for one thing.

"Dude," Sam called, trying to be as loud as possible so as to wake Dean. He was a light sleeper, which was lucky, as Sam didn't want to have to touch him while he was asleep. Startling Dean during his sleep was not advisable without a fire extinguisher present.
"Wh – oh, hey Sammy – I was just, uh – resting my eyes," Dean mumbled, stretching and looking curiously down at his glass, before setting it down on the table.
"Whatever man. Listen . . . About earlier,"
"Sam," Dean began, frowning.
"No, it's just – you're right. I need to get my powers under control, and practise more. I'm sorry. I just . . . I'm gonna need your help. I don't wanna overdo it,"

Dean stared at him thoughtfully for a moment, before half-smiling as he stood up.
"Of course, Sammy. I . . . Yeah. Sure," Dean replied, and Sam knew he'd just gotten his return apology. He smiled at Dean.

"C'mon, let's get you to-" Sam began, but stopped abruptly, freezing in position.
Dean reacted immediately, stiffening and taking Sam by the shoulders. His brother had a far-away, dazed expression on. "Sam? What's wrong?"
"It's Cas, he's-" Sam put his hands to his forehead, wincing, "Fuck, it's – loud," He bit out.
"Let's go," Dean replied shortly, dragging Sam up the stairs at a run, his brother stumbling behind him as the pain subsided.

After running through the many upstairs corridors, they finally arrived at Cas' room. Dean banged on the door:
"Cas, open up – it's Sam, he says you-" Looking at his brother's screwed up face, he sighed and simply tried the handle. Screw privacy. Sammy's head was about to explode, by the looks of it.

The door opened easily when Dean tried the handle: inside, Cas was kneeling in front of his bed, looking up. He appeared to be praying, his hands clasped together with a look of rapturous joy on his face.

"Cas, what are you – what's going on? What's that noise?" Sam asked, gesturing wildly around the room, and Dean figured it was something that only his brother and Cas could sense.
"Sam, Dean – I can hear him," Cas whispered reverently, his eyes alight with happiness.
"Hear what? I can't hear anything but static," Sam asked, rubbing his temple with one hand and supporting himself with a hand on the doorframe with the other.

"His voice," Cas replied. Sam and Dean looked quizzically at each other for a moment, before looking back at Cas who clarified in a matter-of-fact way that left them speechless:
"I can hear the voice of God,"