A/N: I know it's been a very long time since I wrote anything to do with this or SPN/SH crossover in general, but I'm gearing up for Silent Hills to come out, so I thought I'd do a bit more.
A heartbeat passes. Another.
Dean was hoping he wouldn't feel it. He almost wished the sheer size of the blade would shatter his skull so completely it would be over in an instant, but he hadn't been expecting for nothing to happen at all. Gasping, he opens his eyes, and blinks in confusion as he sees the creature has disappeared. A quiet, giddy laugh of relief shakes his chest. He doesn't understand what's going on, but he's still alive, and for now, he'll take that.
With his lungs still burning and his arm throbbing in agony, Dean sucks in several sharp breaths as he collapses to his knees. They sting where they hit the cement, but he barely feels it as he tries to steady his breathing and clear his head. Without explanation, the menacing darkness around him appears to be lifting, ebbing away to the same pale, eerie grey light of earlier filtering through the fog. Dean's good hand drops to the pavement, trying to make sense of what he's seeing. The texture of it is changing, becoming less worn and uneven, like he's watching paint flaking in reverse. None of this makes sense.
Straining to draw one more deep breath, Dean forces himself to his feet again. His arm is starting to go numb, but it's only making it more difficult to think through the ringing in his head. The whole world changed. It did this before: everything changed, and then Sam disappeared. He doesn't know what's going on, but one thing he's sure of is that he still has to keep searching for his brother.
Dean only allows himself a few seconds to recover before starting to move again. He bends to pick up the knife, finding it awkward and unnatural in his left hand, but it's the only weapon – and now the only hand – he has. Then, fighting hard against the pain and exhaustion seeping through his body, he starts to hobble back in the direction he came.
This place is a maze. He's completely disoriented as he tries to find a way out from the labyrinth of alleyways he's trapped in, and it unsettles him further as he becomes more certain that the whole layout of this place has changed from how it was earlier. He can't be sure how long it takes him to find his way out – his watch mysteriously stopped working the moment they arrived in this god-forsaken town – but it feels like at least an hour before he stumbles out into what he thinks is the main street again.
It's difficult to be sure this is even the same place in all the fog. Squinting, he thinks one of the buildings to the left of him might be the diner, but it's growing harder to make out though the haze in his head as well as the surrounding mist. His arm still hasn't stopped bleeding. It went completely numb a while ago, the pain receding to a dull throbbing that Dean can feel all the way up to his shoulder, but he's starting to feel lightheaded from the blood loss. Panic is starting to set in as it becomes more urgent to find Sam before he passes out, but realistically, Dean knows he doesn't have long. His brother could be anywhere. Hell, Dean doesn't even know if Sam's in the same dimension as he is anymore, or what the Hell this place even is. Actually, Hell might just be it.
He keeps walking unsteadily forward, fighting now to even stay upright. Maybe Sam's still by the bridge? What if he never left? Dean knows he can't make it back there. All he's doing by now is praying that even if he dies here, Sam will still manage to find his own way out. Not that praying seems to have done him much good so far.
One foot in front of the other, keep moving forward…
He's wandering further out into the open space between buildings, where the fog seems to be thickest, and it occurs to him that's it's going to leave him near-blind in all directions. He ought to get closer to the buildings, keep a wall behind him, but as he raises his head to try to look around, his gaze lands on what seems like a vague silhouette in the distance.
Dean freezes. It can't be another monster. He physically doesn't have the strength left to fight them off, but he swallows and clutches the knife handle tighter anyway. What's in gonna be, another seriously-overcompensating dude with a pyramid for a head? Or those mutated contortionist freaks? As the silhouette gets closer, Dean can tell it's humanoid, standing upright on two legs. Well, it's not skinless dogs, then. It does at least appear to not have any extra limbs.
"Come on," Dean murmurs under his breath, urging the thing to get closer so they can just get this over with. He's not going to go down without a fight.
His mouth is dry as he watches it approach, squinting to try and better make out the threat through the fog. It's only a few yards away when Dean starts steeling himself to make the first move, not wanting to let the creature call the shots, but his heart leaps in his chest when the figure starts to come into focus. It's not much shorter than him, with very human looking features and wearing a familiar trenchcoat. "Cas?"
The relief that sweeps over Dean is impossible to describe. The angel tilts his head, mouth parting in shock as he takes in Dean's weakened and bloodied state, and then he starts to hurry forward. "Dean!"
With the angel finally here, Dean at last gives up trying to stay upright and sinks in exhaustion to the floor. Cas is by his side in an instant, hands quickly moving to brace his shoulders before he can collapse completely. "Dean?"
The first thought that enters Dean's mind is It's good to see you, man, but the words that leave his lips are, "Where the hell were you?"
Guilt flashes over the angel's face. "I'm sorry, I tried to get here as soon as I could, but it was difficult to find you. Here, Dean, let me…" He's reaching out to press two fingers lightly to Dean's forehead, offering to heal him, and Dean gratefully leans towards the touch. He's expecting this to be quick, healing within the space of a heartbeat that the angel usually provides, but a painful pins-and-needles sensation starts to creep down his arm as he watches the strain on Cas' face. He bites his lip, recognizing that something's wrong, but within a few seconds Cas has overcome it and Dean feels movement return to his shattered arm.
He flexes his fingers briefly before searching Cas' face for an explanation. "What happened?"
Cas gives a shake of his head as if trying to clear it of fog. "This place…it's draining me. It seems as if there's some force blocking my grace." He looks about anxiously, seeming as bewildered and unnerved by their surroundings as Dean is.
The hunter is confused by all of it. "Not that I'm not glad you did, but then how did you get here at all?"
"I couldn't fly in. I found the Impala just outside town, but I had to walk the rest of the way. Even being able to sense where you were was difficult. I could barely hear your prayers. Faint snippets of them, maybe, but it was muffled, like…"
He trails off, eyes flickering around them again, and Dean finishes for him. "Like listening through fog?"
Cas' gaze returns to his face, his expression grave. "Exactly."
That only confirms that Sam's first instincts were right: whatever's causing this weather, it isn't natural.
Grasping at Cas' shoulder to brace himself, Dean clambers to his feet again. The angel helps keep him steady, although Dean can quickly feel his strength returning now that his arm's fixed. "We need to find Sam," he says urgently the minute that he's standing again. "He's gone missing. Can you sense where he is?" The initial relief he'd felt upon seeing Cas is starting to waver as he sees the somber look that enters the angel's eyes.
"Dean, I could barely sense you, but Sam I can't sense at all."
Dean's stomach lurches as he jumps to the worst possible conclusion of what that means. "Right, but that doesn't mean he isn't out there somewhere. We have to find him." He pushes past Cas as he starts walking onwards with a renewed sense of purpose, not wanting to listen if the angel is about to tell him it's futile or that Sam is already gone.
Cas isn't. "Dean, we will find him, but we have to figure out where best to look. What is this place, to start with? How did you end up here?"
"It was meant to be a hunt, Cas. There was somewhere we were headed and we took a wrong turn. I should've just listened to Sam; if I hadn't got lost…" Dean trails off and clenches his jaw in anger directed as himself.
Cas has fallen in step beside him, and he asks the next question cautiously. "What was the hunt?"
"Does it matter?" Dean bites back irritably, but Cas persists.
"Dean, just try and answer. What was the hunt meant to be?"
"It was…" Dean starts to answer confidently, but his voice wavers as he struggles to finish that sentence. "Something in a town nearby, there was…" His pace slows and then he comes to a stop, turning to look at Cas in confusion. "I don't remember. It's like, I'm sure I know, but every time I try and think of it…"
This time it's Cas' turn to finish. "It's like thinking through fog."
Dean says nothing, but he feels an ominous chill run down his spine. He gulps down a deep breath before resuming walking, his pace now even faster than before. "We need to find Sam, and we need to leave," he states bluntly. In any other situation, he'd be wanting more answers about where they are and how to blow this town and all its horrors of the face of the Earth (assuming it's even on Earth and not some outcrop of Hell) but his brother's missing, he's hopelessly unprepared for any of this, and he just wants to get the hell out. "We'll try at the bridge where the river meets the lake. That's where I last saw him," Dean says purposefully, hoping his sense of direction is serving him well enough that he isn't heading completely away from it.
"What happened when he went missing?" Cas is still a couple of paces behind him, but catching up.
"I don't know, man. The world just went seriously weird; everything went all dark and fucked up, and there were these creatures, and we were shooting and running but we didn't know how to stop them…and then they were gone. And so was Sam."
Cas frowns as that sinks in. Nothing about this place makes any sense to him, and for an angel that's battled through Hell's defences as well as watched over the entirety of humanity's existence, finding something he doesn't understand is unnerving. "What do you mean, the world went 'seriously weird'?"
Dean turns to glance back at him. "I mean…" he begins, but no sooner has he started the sentence, the pale light around them begins to grow dim. A palpable rumbling seems to fill the air, too low to be heard, but filled with the threat of violence like crackling static before a thunderstorm. Dean's mouth goes dry as he realizes it's happening again. "You're about to find out."
His eyes meet Cas', subdued horror plain on the angel's face, but Dean feels his own panic kick into overdrive as he watches the world beginning to decay. Even as it grows familiar, it will never cease to be unsettling: the ground peeling, flaking like burnt charcoal as the ashes are carried away in a non-existent breeze. The light grows dim, becoming tainted with red as if the fog itself is bleeding.
What terrifies Dean most is what happens as his eyes lock onto Cas' face.
The angel's skin is cracking, beginning to crumble and disintegrate like the world surrounding him. Dean thinks he can see the shadowy silhouettes of wings behind him, dispersing like smoke, and terror clenches tight in his gut. Cas' eyes widen as he reaches out towards the hunter, calling his name in a voice that's every mix of confusion, panic and fear. "Dean?"
"Cas!" Dean reaches out his own hand, intending to grasp tightly onto Cas and forcibly drag him through into whatever hellish world or reality this is, but his fingers close on nothing but empty air. Cas is gone.
A dog barks in the distance, menacing and unearthly. The world has gone dark.
Dean is alone.