Anoxia
The walls are getting tighter, pressing in like the plates of a bench vice while the ceiling hovers mere inches above his head. His lungs shutter as his chest moves unsteadily, trying desperately to pull in the thinning oxygen. As putrid as the air is, he savors every inhale and regrets every exhale, even if it leaves the musty taste of earth in the back of his throat.
The silence is the worst. Dean can hear his own breathing begin to fail. He can hear the scattered, sharp claws of what sounds like rats (god please don't be rats). He can hear the scuff of his boots against the dirt and the rustle of his jacket. He can hear his own slowing heartbeat in his ears. He's left with nothing but the sounds of his body dying and his own thoughts. Dean's never done well with his own thoughts.
He purposefully doesn't think of his brother. If he thinks of Sam out there alone, possibly dead (he's not dead) then he's really going to lose it. He can't lose it right now. He can't.
He tried to keep the time, at first: seconds into minutes, minutes into hours. He stopped after the first hour and a half. He found that it was hard to panic if you weren't sure how long you've been trapped.
The damp earth soaked through his clothes and pressed up against his skin some time ago, long enough for the chill to fade into numbness. His fingers ache from punching and clawing, and his fingernails feel uncomfortably tight from all the dirt packed underneath them. Dean rhythmically opens and closes his fists just to keep himself from going insane, just so he can feel that little bit of pain and know that he's still alive, to know that he just didn't just lie there and die.
I'm not dead yet, not dead yet, not dead yet.
Something scuttles across his leg. He can feel the scrape of tiny nails and the heavy, brief weight of a tail. For the first time since the start of this ordeal, Dean screams.
He keeps his eyes closed. The longer he stares into the dark the easier it is to see shapeless creatures weave and bob through the tiny space. If he keeps his eyes closed it isn't such a surprise when unconsciousness takes him. Maybe if he keeps his eyes closed, he won't notice when he doesn't wake up again.
It's hours, maybe days later, and his breathing has been reduced to intermittent gasps. As the air in the shallow space thins, Dean starts to lose his grip.
Don't wanna die, don't wanna die, god where's Sammy? Can't get out, let me out, let me out! Sammy…
A hot tear trails down his chilled cheek, burning as it follows down his temple to his ear. It dries and cools as if it was never there. His head's too heavy and his body's too light, and Dean knows this is it; death is one last slip of consciousness away. Even in knowing this, he lets his eyes fall shut, letting the darkness chase away the fear and panic building in the base of his spine.
He wakes to hands pulling and tugging at him, dragging his weight clumsily. He's too weak to stop it.
"Dean? Dean, wake up. You're out. Wake up, Dean. Please…"
Sammy.
Awareness filters in slowly: soft grass under his hands, Sam's hands on his face, fresh air.
He forces his eyes open, trying not to think of the moment when he was sure he closed them for the last time, and stares blearily at Sam's terrified face.
"Thank god," Sam breathes, "Hey, look at me. Deep breathes, ok? Slowly. It's going to be ok, Dean."
He pulls in the air greedily but he still feels like he's coming out of his skin.
Not enough air, not enough space, too close, too close, god the fucking rats.
"You're gonna be ok, Dean," Sam repeats as his hand clamps around Dean's wrist, an attempt to ground his panicking sibling, "It's gonna be ok."
Dean tangles his fingers in the grass under his palms and breathes.