When the light finally crept in through narrow slits, the darkness didn't yet seem to recede. Sam blinked open his eyes, but even the faint twitch seemed enough to dislodge an earthquake in his skull. It was like he was adrift in the middle of the ocean, the cruel waves tossing him beneath their tumultuous rage. His thoughts were a senseless jumble, roiling in a disconnected nightmare.

Distantly, he could taste a familiar pang of bittersweet sulfur on his tongue. It was an anchor of sorts, or maybe a line to draw him back to shore. His best—or perhaps his only—hope at departing the endless sea. He reached for it, he clung to it, because it felt like the only sure thing, the only part that he knew was true. Maybe the only part he wanted to be.

His head was a hive of agony, a swarm of wretched misery. Still, he forced his eyelids apart, though the shapes were slow to form, every wink of light wringing a punishing pulse in his skull. He groaned, raising a hand to massage his forehead—only, something yanked his arm back before it could climb more than a few inches. The sudden realization of his constraint shot a jolt of terror through his chest, jarring the haze of panic like lightning leaping through water.

He managed to pull himself up, managed to force his eyes to focus enough to unveil the blurry outlines of manacles tight on his wrists. Faintly, he could distinguish warding glyphs etched on the metal. His gaze dazedly drifted down toward the dark lines painted across the floor, forming a vast, familiar devil's trap.

Sam squinted as his eyes slowly climbed toward the faintly humming lights above, to the wall with a thin slit down its center. He recognized the space; he knew where he was, though the recognition didn't offer a modicum of comfort.

His arm tugged reflexively against the shackles, but it only earned him the taunting clatter of metal.

The undeniable knowledge of confinement seeped like ice into his bones. It was a rapid unease, a chilling fear he could just barely restrain beneath his skin. It was too familiar a feeling. It rapidly threatened his already thready thoughts with an entirely disjointed collapse. He pulled again against the chains because he couldn't help it, to no greater success than his initial attempt.

He tried to assemble his mind into some semblance of order, into anything that might lend clarity upon the captivity, but as soon as memories began to arrange themselves, he slowed in the effort, suddenly questioning if ignorance had been bliss.

The last thing he remembered was Dean, pummeling him senseless. Had he lost himself to the Mark? Sam couldn't be sure. Couldn't be sure if such an explanation would be better than if he hadn't. He'd only seen a blink of Dean's face through the haze of pain-wrenched tears and dazed nerves. But it had been enough to glimpse the raw rage upon it, the hatred, the wrath. If he had lost control to the Mark… he'd evidently gotten it back. The Mark would've sooner planted iron in his heart than devoted the time and care to wrap it around his wrists.

Sam hadn't been particularly claustrophobic, growing up. He wasn't fond of small spaces, especially when he'd struck his growth spurt, but sometimes they were just part of the job. But ever since he'd gotten back… confinement lent itself to a… discomfort not far from the phobia. He couldn't help the feeling that choked him from the inside. The sensation of something squeezing his throat, pressing in on all sides. The undeniability of vulnerability, of exposure, of helplessness. And right now, the feeling escalated by the second.

He forced a shaky exhale, finding irritation skating over the fear. A flare of anger, that his own brother would lock him up, chain him up like some kind of monster.

He caught the emotion before it could race too far and tried to swallow it down. Tried to remind himself that it wasn't how he felt—not really. It was just… the blood.

The blood that he'd sucked down by the pint, eagerly, hungrily. Desperately. The blood that still vibrated in his veins like it carried a static charge, bouncing along his arteries like excited atoms. That warmed his body like expensive whiskey tossed down the throat. That still tempted his tongue with the sweet reminder of the rich taste, threatening to overtake every sense in its irresistible rapture.

His next breath came shakier than the last. He tried to ignore the fantasies—the memories—that played out in the back of his mind, of the demons at his mercy, the flavor of their fear, the depth of their helplessness—of his control. The thoughts that he should be out there, driving demons to their knees, instead of forced to his own in warded shackles.

No, he shook his head, his arms scraping against the metal so its bite might straighten his thoughts. No, maybe… maybe Dean was right to lock him up.

No—he'd… he'd slipped up, sure, but he could control it. The schedule had been bad, he was behind on a dose, the situation was about as nightmarish as it could've gotten. It was a perfect storm for a relapse—or a re-relapse. It didn't… it didn't mean anything. He could still get clean. The slow detox could still work. They'd go slower, this time, though. It'd be better that way. Surer. Safer.

Or maybe… maybe he was making excuses. Maybe the blood had gotten to his head, maybe he couldn't trust his thoughts, his emotions to be his own—if there was such a distinction.

He wasn't sure how many minutes had passed when footsteps bounced softly in the room ahead, their familiar gait heralding the entrance of a familiar face. The wall—which was merely the back of two bookshelves—pulled apart, revealing Dean looming between them, his shoulders raised and tense, his face dark and twisted, his eyes distant and cold. His entire posture radiated hostility and distrust, perhaps even disdain.

His long pause in the doorway didn't offer much rebuttal to Sam's evaluation.

Sam started quiet, but quick, "How's Cas?" His voice was thick and low, rough, as though blood had congealed in the lining of his throat. He coughed, trying to clear it.

The seconds of silence were painful, an invitation to nightmare, to images of Castiel lying dead, his body pale and void of the ever-present hum of grace beneath his skin. Dean's voice was thin, curt, when he finally spoke. "Alive."

He didn't offer anything more. Maybe that was all there was to say. The only descriptor Dean could offer. The only word he could bear to voice on the matter. And yet, it looked like he was barely restraining a thousand more.

Finally, Sam hazarded breaking the silence, "Dean—"

"What did you do, Sam?" His voice was thick with fury instead of blood, his face reddening to leave no doubt as to the intensity of his wrath. He didn't leave much time to offer an answer—given the question, Sam wasn't sure he expected one. "Why, Sam? What the hell were you thinking?"

"Dean—"

"You said you could handle it. You said you were fine." Dean shouted, closing the distance between them.

"I know; I'm sorry, I—" This time, he cut himself off before Dean even had the chance, suddenly lacking words.

Dean shook his head as though in disbelief—or maybe disgust or wrath—and he pinched the bridge of his nose. "No—what the hell was I thinking?" He scoffed low, his voice unsettlingly quiet—a shift so unexpected it made Sam's gaze snap up, his brow furrowed. "It's not on you."

Sam frowned, waiting for the explanation sure to follow.

"It's not your fault," Dean echoed, a sigh on his tongue, and he seemed to almost deflate slightly, "It's mine." He glanced up, "I shouldn't have let you out. You shouldn't have been anywhere near demons."

"Dean," Sam started again, "Listen—"

"You can't help yourself," Dean stared at him, but it was almost as though he couldn't even see Sam. His expression was guarded, edged in pity and sorrow, but steeled in resolve and… distance. It certainly wasn't a foreign expression to his face, but it was one rarely turned upon Sam. He repeated in that same, cold tone, quietly, as though to remind himself, "It's not your fault."

The words themselves sounded like a balm, like a liberation from the weight of responsibility, but they didn't draw any relief—no, they only stirred deeper apprehension. Sam forced a heavy breath in an attempt to stabilize his words, even as he recoiled against Dean's. "Look, it was a mistake, Dean, and I'm sorry. I just… I—I lost control," the admission tasted like bile, "I'm sorry."

"I know," Dean nodded, but his face didn't shift—like it didn't change anything. Didn't it?

Sam tugged lightly against the heavy chains, causing their clatter to rebound through the room, "Could you, uh… could you get me out of these?" The question was unmistakably wrinkled in tentative hope, concern underlying each syllable, touched with the unshakable unease of the restraints. Hope—hope that maybe the shackles were just a precaution—that Dean wasn't sure in what state Sam would awake. A reasonable safeguard. A temporary one. One that wasn't necessary anymore.

Dean was utterly silent and still for an agonizing few seconds before he met Sam's gaze, "I'm not gonna do that, Sam."

The unease speared deeper, dread spouting like a fountain, "Why?"

"You know." Only the barest notes of sympathy leaked through Dean's stoic mask, "You're not in control of yourself. This is for the best."

The sensation of claustrophobia sank deeper, and the clang of metal echoed through the room, "So what's your plan?" Sam tried to coat the panic in his tone with reason, garnished in thin sarcasm, "Just leave me locked up in here for what, weeks?"

Dean replied readily, unflinching, "If that's what it takes."

"You can't be serious."

Dean didn't reply, his silence answer enough.

The fear crept further up his throat, coloring his voice in undisguisable desperation, "We can talk about this."

"There's nothing to talk about, Sam." His brother shook his head again, "You're sick. You're really sick. And I don't think you realize just how bad. But we're gonna get you better."

The growing haste of his breaths rendered them shallow. "Dean, we agreed to a slow detox for a reason." He held Dean's gaze, slowing his words in hope it might allow them to land clearly. "If you lock me up in here… I'll die." Dean's face twitched ever so slightly—a faint curl of his lip. It was encouragement enough to press, "All of this will have been for nothing. And if Cas… you'll be alone with the Mark." Dean's jaw worked. Sam pressed further. "If you do this, you'll kill me, Dean."

"No, the demon blood is killing you." Dean's voice escalated once more, nearing a grated shout, "And if you aren't locked down, you're gonna go drink more."

Sam gritted his teeth against the sting of the accusation, the distrust, "That's not true." And yet, the fringes of the words seemed to betray a pathetic protest.

"You can't stop yourself," Dean stared at him, almost incredulous, "And I think some part of you knows that." He held Sam's gaze, "That's why you asked me to kill you, if things went too far."

"I know… I know" Sam agreed softly, reeling faintly from the reminder, questioning his words even as they departed his lips. "I meant it. I mean it. But… Dean, it hasn't come to that," His words were more a plea than an argument, his eyes wetter than he'd like, "I'm still me."

Dean wrung his head with a scoff, flinging an arm in the direction of the doorway, "For all your talk of saving people, you just killed three of those demons' meat suits, Sam. And you would've killed them all, if I didn't stop you. Because you couldn't stop."

Sam winced, the undeniable ring of the words tightening his chest. Three more innocent lives to weigh on his soul. Lives he'd taken not to save others, not even to kill the demons before they could hurt someone else. Lives he'd taken merely as collateral damage in satiating his addiction. People he'd killed just so he might savor the taste a little longer.

Low, he forced out again, "I know." He tried to glimpse their faces, but he couldn't distinguish them in his mind. Because he hadn't seen them, not really. Merely the smoke in their veins, the euphoria waiting just beneath their skin.

Dean released a breath, apparently unsatisfied with the reply, brow creasing in frustration, "Sammy, you were so close. You were almost clean. A few days more." His voice was strained with the pain of his disappointment. "And you threw that away."

Sam twisted against the chains, "I didn't—" he swallowed hard and restarted, "It can still work, Dean. We can lay low in the Bunker, find a way to get Cas better, get that Mark off your arm." He wasn't sure how they'd secure more blood, but it wouldn't matter if he couldn't get the shackles off his wrists.

Dean shook his head, almost sadly, "I can't trust you."

"Look, what happened… I lost control," Sam conceded, trying to monitor Dean's reaction, but he didn't seem to be gaining any ground, "But it was just for a moment. I swear."

His brother stared, face cracked in disbelief, "You took that flask from the alley, Sam. And you didn't say a word. You chose to drink it. You chose to use your powers."

"The demon was gonna kill that kid," Sam refuted immediately, and it was true—he didn't have a choice.

"You don't know that." Anger curled Dean's words, "I could've stopped it."

"And if you couldn't?" Silence hung for only a few seconds, but they were long enough, "I had to, Dean. It was a kid."

"Doesn't explain why you took the flask in the first place," Dean replied unflinchingly, "Why you hid it from me." Dean cocked his head, eyes thin, rage still bubbling beneath his skin, "How long have you had blood stashed away?"

"What?" Sam recoiled, frowning, "I haven't—I just… I saw the flask under that dumpster and I—"

"And you hid it from me." Dean repeated, standing over Sam, glaring downward. "Just like you lied to me when you were sneaking out for a hit of Ruby's blood—over and over and over."

"It was a mistake," Sam pled, searching his brother's face. "I don't know why I didn't say anything. I should've told you. I'm sorry."

"The blood messes with your head," Dean pressed, then paced a few steps, exhaling softly to himself, "This isn't even you."

Sam's gut clenched; the words felt so cold, so… isolating. It probably made it easier, rationalizing that he was locking up something other than Sam. He touched his chest, "Dean, look at me. I swear: I'm still me. I'm still your brother." He tried to catch Dean's gaze, but it seemed fixed on the floor. "And if you leave me locked up in here, I'm going to die."

Dean shook his head, "I know you probably believe that. But it's just the blood talking. It's twisting your mind, Sammy." His eyes flicked up, "I promise you, though—I'm gonna get you through this."

Helpless frustration resonated in the rattle of the iron as Dean turned his back to start toward the doorway. "I know I messed up," Sam confessed hastily, voice raw, "I'm sorry, Dean. I'm sorry." Unshed tears threatened his vision. Dean didn't know what it was like. He couldn't understand. He couldn't bear to see. "Please. Don't do this."

"You're gonna have to trust me on this, Sam." Dean murmured from the entrance, not meeting Sam's face, "This is for your own good."

"Please, don't leave me here—" Sam begged, yanking against the shackles, but Dean was already gone, the wall sealing in place behind him. The echo died quietly on his tongue, "Please."

Without the glow of the storage room, the light above was cold, dim, the shadows heavy, stretching out from every corner. Alone, the air suddenly felt thinner; it was hard to breathe. The iron felt heavier on his bones, the manacles tighter, hungrier on his skin.

He knew what was coming, even while he didn't.

He was going to die on his knees, his body chained to the floor. Probably with vomit frothing his lips, sweat drenching his skin, eyes bloodshot and sunken deep, seeping glassy tears of crimson. Alone.

And when he woke up, he'd find himself bound in grace like iron, bent to his knees, his body an offering ready for the breaking. Alone, with the Devil, forevermore.

He'd die here. But first, he'd suffer the closest thing to hell he'd ever known topside.

He screamed through gritted teeth at the utter unshakable feeling of helplessness. It was far from a novel sensation, but he hated it. It drove his mind into an unsteady panic; though he tried to measure his breath and suppress it, the fear flirted with shattering the thin stability he'd managed to construct since his return. Impulsively, he tried to stretch out his power—anything for a modicum of control—but it wouldn't leap beyond his skin. His gaze slid to the warding on the shackles, and he threw his arm downward in frustration, the metal cutting into his skin and freeing a thin stream of blood. His eyes lingered on the beads before he wrenched his gaze away. It wouldn't help. The taste would just further frenzy his mind. And yet, he knew it wouldn't be long before he'd be sucking it down anyway. The realization tasted bitter.

Maybe… maybe Dean was right. Maybe he was out of control. Maybe this was for the best.

And yet, everything in him strained against it, because it was wrong. It was death—it was agony. It was abandoning his brother and friend. It was a torture he couldn't endure. It was dying a pointless death. It was condemning Dean to an eternity with the Mark, alone, and Cas a few final days of mortal misery. It was the vast clutches of the Cage dragging his soul back to Hell, proffering it on a silver platter to Lucifer, who had had hundreds of years to contemplate the proper punishment for Sam's undue departure.

A chill crept along his neck like the breath of a whisper, and he winced, glancing over his shoulder, but the shadows hung like thick curtains around him.

The silence was oppressive, and his heart took to flood it with a rising pound, pulsing in his head almost mockingly with every beat.

His body ignored his fevered attempts to quell his rising panic—it had been well conditioned to the grip of chains. It was intimately familiar with what always followed.

A soft clicking in the shadows sent his head snapping to the noise, eyes wide as they fought to distinguish a shape in the dark. No… it wasn't a click—it was a tsk. When he yanked against the chains subconsciously, it slowly morphed into a laugh, consuming the room in malignant mirth.

In the depths of the darkness, a pair of eyes flashed yellow.

"Hello, Sammy."