Castiel can feel his wings burning. Pain, white-hot, nearly overtakes his senses. He wants to stop, to rest, to heal himself, but he cannot. The longer he takes, the longer the Righteous Man suffers. He has been sent to save the Righteous Man, along with a battalion of angles, but now, he is the only one left. Castiel has never felt so alone in the thousands of years he has lived. The deeper into Hell he flies, the more he can feel is Grace fading.
A scream rips from the silence toward his left. Instinctively, he flinches away from it. But even as he does, he catches a glimpse of a faint, watery shine. He sucks in a surprised breath, ash suddenly coating his throat. The Righteous Man. Castiel has found him. He turns, scanning the area around him, before approaching slowly.
The Righteous Man is not smiling, and the light of his soul is flickering. A soul is strapped to a table in front of him, held down by sharply barbed metal straps. The soul is missing several fingers and toes, as well as an ear. The Righteous Man chooses an extremely rusted knife from an arsenal of weapons. He slices a thin line across the soul's throat, and the soul begins thrashing around, screaming and pleading to be released.
Castiel remains in the shadows, suddenly unsure of his mission. The Righteous Man's soul shines, but it has become watery. It is infected. Black smoke curls around the edges of the light, tendrils reaching in to pierce at the center, where it remains the most pure. As the Righteous Man plunges the knife into the trapped soul's chest, his own soul flickers dangerously. The black smoke suddenly solidifies at the outer edges. Castiel can feel his panic rising at the sight. The trapped soul is screaming, bloodcurdling and frightening.
With one swift, experienced movement, the Righteous Man twists the blade deeper into the trapped soul, an ugly sort of satisfaction crossing his face. He steps away from the soul, reaching for another instrument of torture. Castiel takes this moment to step from the shadows, his wings raised as if on high alert.
"Stop."
The Righteous Man turns immediately, a new knife clutched in his hand. "Who are you? What do you want?"
His green eyes are clouded and dark, as if the blackness gnawing at his soul is also overtaking his sight. His stance is defensive- one hand raised to block a punch, the other clutching the knife, knees bent slightly, ready to spring into battle. The black clouds in his eyes flicker and become darker. Before Castiel can answer him, the startled look fades from the Righteous Man's face. He breaks into laughter. The soul behind him begins to squirm again, blood coursing down its chest and trickling from the corner of its mouth. The Righteous Man turns, still laughing, and releases the soul. The soul stays for a moment, wary, before bolting off into the darkness.
"Dean Winchester, Righteous Man, I am here to raise you from perdition and save you from your suffering."
Castiel uses a sliver of his Grace to watch Dean's soul. The moment his name is said, the blackness gives a dangerous spark before surging inward to invade the pure ness at the center of his soul. The Righteous Man, Dean, watches the angel for a long moment. He tosses the knife away with a sigh of relief.
"Alright, gorgeous. Let's do this thing. Get me out of here."
Castiel lets his wings fall to a more comfortable position, his feathers charred and smoking. He reaches out a hand and lays it on Dean's shoulder. Dean raises his eyes from the ground and stares right at Castiel. In that moment, Castiel realizes his mistake.
Dean's hand darts up and takes a vice like grip on Castiel's wrist. He twists the wrist, hard, and Castiel cries out. In the moment that the angel's defenses are down, Dean shoves him backward.
Castiel's wings flare up behind him, but his fall is broken by the thud of a table meeting his back. Chains of burning silver appear and lash him down by his wrists and ankles. Dean steps forward, his green eyes now black, a wicked smile on his lips.
"You are a pretty one, angel, aren't you? But you're too late."
Dean reaches off to the side and picks up yet another knife, this time gleaming and wickedly sharp. "Why don't we see if you're as pretty on the inside as you are on the outside?"
Castiel beats his wings once, twice, to no avail. The stench of burning flesh fills his nostrils, and from the pain corroding his senses, he knows it's the skin underneath the chains. His wings beat once again behind him, hindered by the table, before falling limp. The knife runs across his chest, hardly touching the skin and yet drawing blood. He is trapped. He has failed.

Dean keeps him there for a week, disappearing each night and leaving Castiel bound to the table. Each morning he reappears with a new stock of weapons to torture the angel with. On the eighth day, Castiel has had enough. There is a mere splinter of light left in the Righteous Man's soul, but it's enough. The moment Dean appears from the darkness, wielding a burning torch, Castiel begins to speak.
At first, he quotes the Scriptures. When it has almost no effect, he resorts to telling Dean about his own life. Slowly, with every passing mention of the people he's saved, of his brother Sam, Dean's soul begins to expel the blackness. Finally, he breaks into tears and collapses on the ground. The chains binding Castiel vanish. As the angel steps off the table, his wings raise behind him, only partially healed. Dean raises his head to look at Castiel with pleading eyes.
"Please. Save me, please, don't leave me here."
Castiel does not make the same mistake as before. He searches Dean's soul before touching him. A haze remains in the lightness of it, remnants of his near transformation into a demonic creature. It is nearly pure again.
"Dean Winchester, Righteous Man, I am here to raise you from perdition and save you from your suffering. Do you, in the presence of an Angel of The Lord, confess your sins and wish to be saved?"
"Yes. Yes, please. Don't let them change me."
"In the name of The Lord, may your soul be at peace."
Castiel reaches down and places his hand on Dean's shoulder. He sends a pulse of his Grace through his palm, searing Dean's skin. Dean crumples to the ground, unconscious. His face is smooth and free of pain. Castiel gathers Dean into his arms, spreading his wings for flight.
The Righteous Man is saved.