The loud creak of the heavy metal door echoed through the dimly lit space. Castiel glanced toward the war room, pushing back from the table and abandoning the tome to approach the sound, pausing only to nudge the small trashcan beneath the table—lest someone glimpse the crimson stains on the tissues within.

Dean appeared first at the head of the stairs, his face drawn, eyes shadowed in a blend of fatigue and worry, meeting Castiel's gaze only momentarily before he looked backward as his brother appeared in the doorway. Castiel's breath caught at the sight. Sam looked and moved almost as a ghost of himself, his movements jarred and sluggish, his gaze fixed on the ground, not registering his surroundings, his skin pale and ghastly, eyes sunken deep and dark.

The sight stilled the very words in Castiel's throat, robbed the greeting from his lips.

Silently, and without raising his gaze, Sam descended the stairs and numbly drifted across the room, disappearing into the long hallway. Though they couldn't hear it, Castiel knew Sam had almost certainly sealed himself in his bedroom, behind a softly closed door.

By the time the angel turned, Dean had reached the base of the stairs, his body heavy with exhaustion. The older Winchester's expression was taut, his lips pressed into a thin line, offering little solace to the turmoil contaminating the air.

Dean met Castiel's eyes, his own a war of weariness and an urgent concern. "He's… not good, Cas." His voice was low, as though speaking any louder might shatter the thin glass that suspended their collapse.

"What happened?" Castiel asked, brow furrowing, searching the Winchester for answers even before he could speak.

Dean huffed an exhale—as though it might be easier to list what hadn't happened. "We, uh…" he set a metal box, etched with white protective sigils upon the war table, sliding it away as though to distance it from himself. Castiel's gaze immediately dropped to the box, to the shadows and crimson tendrils coiling in a vibrant, poisonous smog, leaking through the perfect warding that should've isolated it within its seals. "We found the book Sam was after."

Castiel frowned, eyes flicking upward, "The Book of the Damned?"

Dean nodded, brow furrowed, "I think… something might be wrong with the warding."

Castiel reached toward the box, hesitating briefly, before daring to grasp it. The mere touch of the container felt defiling, filthy. And yet, the sigils were unblemished, their lines precise and true. He returned it to the table, "The warding seems intact…" Castiel glanced toward Dean, "Can you… sense it, Dean?"

Dean's gaze was furtive, wary, "I dunno. I… Cas, it's like..." he scratched at the crook of his elbow—at the Mark on his arm.

"The Mark of Cain," Castiel concluded, his words only holding a slight question, "It's… reacting to the Book."

Dean was slow to speak, his voice quiet when he did, "I think Sam could feel it too."

His frown sank further, "Through the warding?"

Another nod, then a searching gaze, as though to evaluate Castiel's reaction to the information—to gauge how worried he should be.

"The Book's influence is strong," Castiel supposed, trying to mask his skepticism of the very words he voiced, "It's possible any human might feel it, even through the warding."

Dean's expression didn't shift—he wasn't convinced. He leaned back against the table, crossing his arms.

"There's something else, too." Castiel's expression tightened at the portent, silent as Dean continued, "Gideon, the hunter guarding the book, he… he had this charm. A cross. Said it could sniff out demons—put 'em through hell." He seemed to struggle with voicing his next words, "Cas… it almost killed Sam."

Alarm captured Castiel's face, eyes widening somewhat, "Because of the demon blood?"

Dean shrugged helplessly, "What else could it be?"

The angel paused to organize his thoughts, uncomfortably aware of Dean's impatient, nervous glances. "The obvious explanation is that the charm is somehow tuned to a demonic essence, and that the demon blood in Sam's veins merely reacted like… metal might to a magnet," Dean didn't seem encouraged, so Castiel clarified, "It doesn't mean Sam's become a demon."

"I know—he can cross devil's traps, and far as I know, he doesn't burn under holy water." Dean dismissed, but he didn't seem entirely put at ease despite his own assurances. He released a heavy exhale, as though trying to release his disquiet, "Cas, I don't know what that thing did to him. He started seizing—bad. Wouldn't stop until Gideon put the charm away." His face seemed to pale at the memory, weaving sympathy in Castiel's chest. "Gideon seemed to think Sam was the antichrist. Warned me not to let him near the Book."

Castiel hesitated. Dean wasn't sharing the details for a therapeutic release—he was still watching Castiel closely, carefully. "Dean… he wouldn't be the first hunter to believe in Sam's… destiny."

"No, I know that, I just…" He seemed to struggle with the question, conflicted as to whether voicing it would constitute a betrayal. Evidently, worry won out over sensitivity. "Is it safe, having the Book here? I mean, when he's hopped up on demon blood."

The angel looked over Dean, trying to stifle a cough, "It may hold the cure for the Mark."

Dean shook his head, "I don't want to risk losing all the progress he's made for another longshot to get rid of this thing."

"The spells contained in this Book are very powerful, Dean," Castiel pointed at the warded box, "They're not simple charms or incantations like we've tried before. If there's a spell that can remove the curse… there's a strong chance it's somewhere within this text."

"At what cost, though?" Dean rebutted, "Mojo like that never comes free."

He was right; there'd be a price, because there always was. But the Mark wouldn't resolve itself, and their leads were getting slimmer by the day. Aside from Cain—and, Castiel's mind mused traitorously, Lucifer—they didn't have a solid lead. "We can't afford to ignore this."

"I'm not trading this Mark for Sam to take on something worse."

"It won't come to that," the angel averred, tilting his head as he looked over Dean, "We don't even know what's inside the Book yet."

"Exactly," the harshness of Dean's tone seemed to give even himself pause. "Look—that Book is evil, Cas. I can feel it. The Mark's itching for me to crack it open right now. And I don't think that's because it's just gonna freely give us the cure." He dropped his gaze, "I'm just saying… it might not be worth the risk, opening it."

"It could cure you, Dean." Castiel repeated, tone edged in disbelief. "Of course that's worth the risk." Dean exhaled through his teeth, shaking his head. The angel started slowly, "I understand your caution. And I agree, precautions should be taken. Given the nature of the Mark, it would probably be best if you maintained distance from the tome. But I could attempt to find the cure, with minimal risk."

Dean stared at him a moment, "Are you sure that's safe?"

He raised his shoulders, "It's impossible to be certain. However, even with my decline, my remaining grace should prove a safeguard—a filter, of sorts—to any undue influence from the text."

Dean scoffed low, muttering, "As if your grace's protected you from that before." Castiel's head dropped, and Dean seemed to catch himself, "Sorry." The angel acknowledged the remark with a silent nod. He'd succumbed to undue influence a few too many times in the past, and it had cost him and those closest to him greatly. How many people had to pay for his mistakes before he learned? How many people had to die?

And yet… his stance remained unfazed. If there was a chance it'd save Dean… he had to try.

"Alright," Dean raised his hands in surrender, backing away from the table, "See what it says, then."

Castiel dragged the box closer, gingerly unlatching the locks. Immediately upon raising the lid, his stomach plummeted, and brain swayed in nauseated disorientation. He forced a steadying breath, glancing up toward Dean, glimpsing what he almost thought was a spark of wary hope. That, perhaps, Castiel might actually proffer a way to free himself of the curse tainting his body and mind. Spurred by the thought, the angel carefully reached inside and withdrew the heavy tome, setting it upon the table with a measured authority. He had to force his hands to bend back the cover, to unfurl the pages, had to force his gaze to land upon the ink—only, the text was dark and roiling, a black haze in his sight. Clearer than letters, he could read the raw evil and torment and sadistic delight etched into every stroke. It rose up from the page like a tempest sweeping in from the sea, like smoke birthed from an inferno, snaking toward him with an undeniable hatred. Every ounce of the tome felt like a desecration; all the grace within him wanted nothing more than to scourge the filth from his presence, to cast it far into the abyss where it belonged. And he couldn't help but realize it mirrored his sentiment, its dark wrath tightening around his throat like a tangible coil, or perhaps seeking to dance even higher, to gouge his eyes from his skull to rid their holy gaze from marring its awful presence.

"Cas!" Dean's voice, raised in a shout, freed the invisible, intangible shackles from the angel's hands, and he instantly snapped the Book closed. Staring at him, clearly unsettled, the hunter prodded, "The hell was that?"

Castiel blinked at the tome, head still swaying. "I'm not sure. I think the Book… doesn't want me to read it." Its black tendrils crept towards his hands, their malice radiating like heat.

Dean frowned, "What?"

Even as he spoke, a swoon of dizziness threatened to overtake him. It was almost like… almost like the Book had begun to deplete his grace, either sucking its power or possibly merely squelching it beneath its impure touch—Castiel couldn't be sure. With no small degree of haste, he swept the book into the box, firmly shutting the lid and latching the locks to reseal the warding. Its presence didn't vanish, but it abated almost immediately, like someone had flicked a light switch to banish the vast shadows consuming a room.

"I think…" Castiel dared a glance away from the box, selecting his words cautiously as his gut coiled in knots. "It's not designed for an angel's eyes."

Dean gritted his teeth, stepping back and wringing his head. After a moment, he muttered, "This was a waste of time. Should've never gone after this thing. Should've known better."

Castiel's brow furrowed. Though his sight hadn't quite steadied, he could feel Dean's frustration crackling off his skin like a scarlet storm. Why was he so quick to accept failure? "We'll find someone who can read it."

"Yeah, who are we gonna trust with that?" he gestured toward the box, "You can't read it, I don't want to be near that thing, and I'm not letting Sam within a hundred yards of it—not in his state."

"Dean—we'll figure it out." Castiel assured, trying to temper Dean's roiling irritation, though he still felt as steady as a raft at sea. They weren't out of options yet—and they wouldn't be, not until Dean was cured. He wasn't to be sentenced to an eternity with the Mark—not at the bottom of the sea, not roaming the lonely Earth. Castiel wouldn't allow it.

Dean shook his head in disbelief, "Yeah? Like we've figured out Sam's addiction? Like we've figured out your grace?"

"Sam is improving," Castiel countered, not permitting his voice to rise to match Dean's—not sure it had the strength to.

The Winchester scoffed derisively, "You and I both know that's not true. He's trying to hide it, but he's getting worse, not better."

"We knew the detoxification wouldn't be easy." Sam's schedule demanded aggressive dosage reduction. Even if it wasn't a strict and clean cutoff, they knew Sam would still suffer the symptoms of withdrawals—for even longer, in fact. His decline was concerning, but perhaps it should have been expected. Perhaps it didn't mean he wouldn't improve.

Dean couldn't meet his gaze, his words lethally slow and quiet, "It might be killing him, Cas."

The angel paused, the situation weighing heavily upon him, "Perhaps we should extend the schedule." Maybe, even amended, his schedule was overly ambitious. It was all little more than guesswork, by Sam's own admission. Castiel knew he wanted to get clean as quickly as possible, but… maybe they were taking things too far. Maybe he was pushing himself too hard.

Dean wrung his head, "It's poison. Every time I give it to him, it's like…" his words dropped off. He sighed, looking up toward Castiel, "Is there any other way? Anything that'll help?" His eyes betrayed the thread of hope behind the query, the desperation at the edges of his tone.

The angel went silent to consider the question, his mind racing through celestial knowledge and occult lore, but he finally dropped Dean's gaze, "I'm sorry, Dean, but I don't know of any other way. His… condition, isn't as simple as your own transformation as a demon, beneath the Mark's influence." As if there'd been anything simple about even that. "I don't know how the Rite of Sanctified Blood would affect him." In fairness, they didn't know how it would affect Dean either—in trying to cure him, they faced the strong possibility it might kill him. And yet, for Dean, they at least knew the state they were trying to revert him to; they at least knew he had existed in such a demon-free state before the Mark revived him with black eyes. Sam, on the other hand… he'd been infected with demon blood almost since birth. It wasn't something they could just… extract. It had become a part of him. It was like trying to tear out from a tree the very water and soil that had sprouted its growth from a seed. The infection had changed him, had shaped him, had molded him since that fateful night. There wasn't a Sam Winchester without it. Even when he'd died and been resurrected, by angels and demons and God Himself, the infection remained. To try to kill it was to try to kill a part of him. Castiel found himself doubtful that Sam could even hope to survive such an attempt to fully cleanse him of his curse. No… they just needed to return him to a balance. To set his body back in equilibrium so he didn't need to satisfy the pangs of his withdrawals with the infernal blood.

Dean wiped his hands over his face, a motion that highlighted the fatigue bearing upon his shoulders. He nodded, murmuring, "I know…" After a few seconds of agonized stillness, Dean sighed, checking his watch, "It's, uh… Sam's… overdue for his next dose, I think. We… lost the rest we had, so… we're gonna need some more, soon, probably."

Castiel tilted his head in understanding, hopeful he could find another demon as promptly as the last. At Dean's careful phrasing, though, concern rose in the angel's chest, and he invited further explanation with cautious hesitation of his own, "Sam mentioned you ran into trouble on your hunt." Perhaps that was why Sam sounded so disheartened on their call, despite his resistance of the blood's call?

Dean raised an eyebrow, then shook his head, "No—I mean, yeah, but we lost the bl—" he cut himself off with a curl of his lips, correcting, "The flask at Gideon's." He rubbed his ear, scoffing in something not far from surprise, "He shot it right outta my hand. Think I can still hear the ringing."

The angel extended a hand crossing the distance as he stretched his grace along his fingertips—an exercise that demanded greater strength than it should've. Dean batted Castiel's hand away, his gaze low, refusing to meet Castiel's, his tone terse, "I'm fine. You've gotta conserve your grace, Cas. Still need you around with everything going on."

Castiel's chest tightened and jaw clenched at the words, though he wasn't entirely sure of the emotions that bubbled within. Still, he respected the verdict and retreated a step, his posture stiff as he cleared his throat, "I… left the demon blood in your room, as instructed." He'd only retrieved a single bottle, given the prompt turnaround and his presumption that Sam and Dean carried enough for a few days' worth of doses.

Dean managed to glance up and nod slowly, seeming to contemplate with a faint thread of guilt. "Aright," he finally spoke, beginning to angle his body toward the hall, "You, uh… you know how much to give him?" The angel nodded, determining that Dean wasn't prepared to increase the dosage to further mitigate the withdrawals, at least not yet. "Then… go ahead. But don't let him convince you to give him any more, okay?" Even as his brows furrowed, Castiel heard the pain underlying Dean's words, the concern and fear needling them. "And, uh… take it easy on him. He's…" Dean shook his head, abandoning the sentence, his silence finishing it in his wake.

Castiel couldn't deny the surprise and confusion blending in a cocktail of concern in his chest. Dean had very explicitly controlled the administration of Sam's doses. Why surrender one to Castiel now? Particularly when the Winchester seemed so worried about his brother. Cautiously, he dared to ask, presuming the hunter would gather his meaning, "Are you sure, Dean?"

Dean hesitated, as though considering whether to answer. When he did, his reply was slow, quiet, "He didn't want to talk to me, Cas. I think… I think he wants some space."

The angel was silent as he considered Dean and his explanation, skepticism and worry intertwining in his veins. Something must have happened, something more severe than Dean was willing to disclose presently. The angel didn't like stepping between the Winchesters' turmoil, but if Dean was desperate enough to abate his strict control over Sam's recovery… Castiel couldn't refuse him.

"I'll see to him, then," he replied quietly, and Dean nodded once in gratitude or acknowledgment.

As the angel turned to depart down the hall, his steps unusually heavy, Dean cleared his throat, his voice tight with trepidation, "…Cas?"

He paused, glancing over his shoulder.

"Let me know how he's doing… after."

After the dosage, or after the check-in? Castiel wasn't sure which Dean meant—what he was seeking. But, given how intimately the brothers knew each other… he couldn't help but think Dean already possessed a strong idea of Sam's current state, especially given they'd barely been apart in the past twenty-four hours. Still, despite the attempted mask of casualness, Dean's concern weighed heavy in every syllable. Maybe he knew… maybe he just wanted to be wrong.

Castiel nodded and resumed his course down the hall, trying to muffle his cough and stopping briefly in Dean's room to root the bottle of demon blood from the cooler tucked within a chest at the foot of Dean's bed and a clean syringe, before starting slowly towards Sam's room. He wasn't particularly eager to bother Sam, to intrude on his space, if he blatantly wanted to be left alone. The angel couldn't help but think he'd earned the right to such a minimum degree of privacy, given all he'd endured over the past couple weeks—no, months, if not years.

Still, he rapped softly upon the door, his voice low, the single word tainted in the concern he couldn't snuff, "Sam?"

There was no response—merely the muted shuffle of movement from within. Unfortunately, the knock could only be a simple courtesy, an announcement, rather than a true request. He inhaled deeply, then twisted the handle, peering into the dimly lit room.

Sam was perched at the edge of the bed, curled away from the door, his head in his hands, his leg rapping fervently. His hair hung over his face, his shoulders quaking somewhat with the rapid jitter of his leg. The air around him buzzed with an anxious hazy crimson, an uneasy pale yellow, the shadows of the room seeming to stretch towards him both menacingly and tenderly.

"Sam?" Castiel repeated gently, slowly navigating around the bed so as to enter Sam's field of vision.

The Winchester glanced upward, revealing the pallor of his face, the sink of his dark eyes, the crackle of raw pain that struck deep, to his very core. The gouges along his soul, the scars from the Cage, flaring, bleeding in ugly torment as though reaggravated.

At the slight surprise and worry that pierced Castiel's normally impassive mask, Sam dropped his gaze, his hair once again shielding his face, his shame and guilt almost tangible.

"How are you feeling?" Castiel asked carefully, though the color of the truth was palpable.

Sam shook his head, his voice rough, quiet, tenuous, "Does it matter?"

To the angel and his brother, perhaps, but not to their circumstances. "I'm sorry." The words felt like a candle tossed into the depths of a blizzard.

Sam didn't react, unmoving but for the relentless tap of his leg.

Castiel halted well within Sam's scope of vision, if only the latter raised his head. He lifted the flask slightly, "Sam… I believe it's time."

Sam's lip curled almost immediately, his head twisting along with his expression. Castiel could only speculate as to the thoughts lurking behind the man's eyes, but he could read the revulsion on his face. After a few seconds, Sam shook his head, "No."

Bewilderment wrought a heavy pause. Castiel frowned, undeniably surprised. He'd witnessed Sam's… desperation for the blood a few times prior. Unsettling as it was, the angel reminded himself it was merely the trademark of addiction. Pity and worry had swarmed in his chest at the sight, to glimpse a friend reduced to the demands of a primal drive. And yet… Sam's sudden and inexplicable resistance proved almost equally as unsettling, if not more so.

"What?" Castiel asked, trying to pace his tone in a steady flow, controlling the worry and unease.

"I don't want it," Sam's voice was a whisper, barely audible. A confession, hanging in the air. His eyes, glassy and distant, stared unseeing into space, almost as though he'd forgotten Castiel's presence entirely.

The angel's brow furrowed, his confusion mounting. The attestation seemed in stark contrast to what he'd seen in the Winchester, to what Sam had admitted before, to Dean and to Castiel. Instead of disputing, he dared a step closer, asking guardedly, "Why?"

Sam's eyes didn't shift, but his expression contorted with pain and emotion, "I… I can't keep doing this, Cas."

Castiel held the flask steady, his expression solemn, "Sam… you know what will happen if you don't take this. The withdrawals… they'll get worse. They could kill you."

Sam released a soft, fatalistic exhale, "Maybe that's for the best."

Castiel felt something tighten in his chest. He hated the words even as they fell upon his ears. He clenched his jaw, his voice solid as stone, "That's not an option, Sam." Why would he suggest such a thing?

Sam glanced upward, his eyes searching Castiel's somewhat fervently, then sliding away in a blend of realization, frustration, and defeat. "Right…" his words were murmured, almost breathless, "Because I don't have a choice."

Castiel despised the implications of the statement. Even if he thought it might not be entirely without merit. He couldn't envision Dean allowing Sam to succumb to his withdrawals, not so long as he believed they'd exact Sam's end. Not anymore. Not since he'd lived a long, lonely year in the safety of the suburbs, while his brother suffered agonies beyond even angelic comprehension beneath the intimate attentions of the Devil himself. No, he couldn't think Dean would allow Sam death, even if the latter sought it as a mercy. And, at the moment… Castiel couldn't find it in himself to stand in Dean's way, despite the misery clinging to the man before him like heat to a fire.

Sam seemed to sink further at the apparent confirmation of his understanding, his shoulders curling, head dropping.

"We're not losing you." Castiel proffered firmly, in an attempt to properly frame the notion.

Sam's brief, feeble laugh was bitter, "Maybe… maybe I'm lost either way." He glanced back into the angel's eyes, his own lost in turmoil and desperation. In a plea for understanding. "I stop, it might just kill me. I don't stop… I might not be me anymore."

Castiel felt his heart twinge, his stomach plummet, like when he folded his wings tight to his back a thousand feet in the air. He tried to level his voice, so it wouldn't share the sentiment, "It's not permanent, Sam. It's only until your condition is… stable."

"We don't even know if I can get clean from this. At least, not while I'm alive." The Winchester shook his head, "Every time I take it, it gets harder to think about stopping." His jaw trembled slightly, "I… I don't know if I can."

The angel went silent for a moment, considering his reply while his heart panged for the torment that bedeviled his friend. "Sam," he started slowly, "This is proof that you're in control of this." That Sam was genuinely trying to cut himself off, even in the face of probable death. That, when blood was proffered, time and again, Sam refused. Castiel didn't doubt that the hunger still clawed at Sam as madly as before. His body still yearning, still screaming for the relief, the tantalizing power of the blood. And yet… he still resisted. "You told me you ran into demons on your hunt. You could've drunk their blood." The angel continued, trying to pace his words in both gentleness and resolve, "But you didn't. You're more capable than you give yourself credit for."

Sam twitched at the mention of the demons, a reaction that caused Castiel to tilt his head, though the Winchester extended no explanation. It seemed to reignite the vigor in his fidgety jitter. He rose to his feet quickly, pacing a few steps as he raked his fingers through his tousled hair.

"Sam," he tried again, the flask in his hands feeling more like a grenade that had shorn its pin than the mere medicine he wanted to consider it. "It's temporary. You'll get through this. You have before." Perhaps not the withdrawals, at least perhaps not in the same way, but Sam had controlled his addiction for years. Sam was strong. He'd overcome Lucifer just before the Devil could demolish the world. He could overcome this.

Pausing in his pacing, Sam held Castiel's gaze, his voice a quiet appeal, "Cas… please."

The plea might as well have been daggers in his chest. He couldn't do what Sam asked. He tightened his grip on the flask. Sam… was merely suffering the effects of the withdrawals, Castiel rationalized. He was behind on his dosage, and it was exacting a heavy toll on the already exhausted Winchester. He'd improve… and he'd be back to himself soon enough.

"I'm sorry," the angel apologized, his gaze sincere, his pain framing his words, his already heavy heart weighing heavier in his chest.

Sam twisted his head away, his breath audible. Yet, his resistance faded quickly—not because of the demon blood's call, perhaps, but because he realized he had no option. That, even in this, even in his fight to regain control, he had none. Almost numbly, he returned to the edge of the bed and began to roll up a sleeve, exposing his flesh and offering his veins to the treatment.

Uneasily, Castiel withdrew the syringe and measured out the dose, sealing the flask and tucking it away before turning his attention fully to the Winchester, if for nothing else than to rid his focus from the impurity that was the blood. He grasped Sam's arm to steady it, his brow furrowing faintly at the starkly warm temperature. Pushing aside the concern, he guided the needle toward the blue vein bulging at the crook of Sam's elbow—it wasn't difficult to locate, as though his body was eager to simplify and hasten the process as much as it could.

He felt Sam's muscles tense beneath his grip, a grimace carving itself across his features—not to brace for the pain, but for the relief he dreaded and desired in unequal measure.

Before he could change his mind, Castiel pressed the needle into Sam's skin, administering the dose steadily and daring to lift his eyes from the syringe to monitor Sam's reaction.

The effect was almost immediate. Sam's face softened slightly, his body relaxing visibly with the relief that followed, though tainted by the disgust at his own dependency. His body was still heavy with fatigue, still sunken with pain, but he seemed both somewhat less and somewhat more… hollow.

As soon as the needle had departed from his flesh, Sam shifted to semi-cradle the arm, rubbing the crook of his elbow and smearing the small rising bead of blood in the process. He didn't glance toward it, but Castiel was reasonably sure he'd noticed.

The angel capped the syringe and stuffed it into his coat, stretching a hand toward Sam's forehead. Even in the mere second and a half of contact, before Sam pulled away with a scowl, Castiel's concern climbed steadily.

"Sam… your temperature is 109." The angel couldn't conceal the alarm from his tone, his eyes now skirting over Sam in a new evaluation. He should have noticed the fever; it clung to Sam in a sickly sweat. Silently, Castiel cursed himself and the fading of his angelic sight, the climbing fog treading at the corners of his mind.

Sam's scowl deepened, tainted in confusion, "That's impossible."

Castiel interpreted the disbelief as an invitation, if not a challenge, to verify his reading. He pressed his palm to Sam's forehead again, the Winchester only stiffening this time and not pulling away. "How are you feeling?" he asked again, this time in a genuine search for answers. The temperature remained the same. But Sam was right—he shouldn't be conscious, sitting upright, communicating with relative ease. Such a temperature threatened vital organ damage—death.

"Not great, but… not like hyperpyrexia." Sam's gaze dropped to his forearms, lingering on the crook of his elbow, as though identifying the suspect.

Castiel closed his eyes and, his hand still pressed against Sam's head, began mentally tracing the path of Sam's organs with no small degree of effort. His brain seemed highly stimulated, yet the angel found no signs of heat damage. His inspection traveled downward, hastily skimming every organ for a sign of the expected deterioration—but, though Sam's body was in undeniable disarray, Castiel couldn't find any damage from the temperature. His heart beat notably faster, clocking in at a steady 120 bpm—though perhaps it was merely a pace prompted by anxiety, or his body's attempt to rapidly circulate the strength of the poison. A twinge of guilt tore at him for the feeling of impurity as he withdrew and reopened his eyes. Sam's every cell was contaminated with the unholy shadow. And, though the infection seemed to wage war on him, the temperature… strangely, didn't seem to be provoking issue.

"What?" Sam demanded, clearly reading the disturbed look upon Castiel's face as he retreated a few steps to allot the Winchester space.

"I'm not sure," Castiel admitted, voice terse, finding himself unsteady on his feet as his grace stuttered to resume its flow through his body. "A temperature that high is typically fatal to a human. But… it doesn't seem to be causing your body any damage."

Sam blinked, then his head fell as though in realization, "Right… because… I'm not human."

"That's not what I meant," Castiel murmured, looking over the Winchester in pity and dismay.

"I know," Sam dismissed, ducking his head, "Shouldn't be surprised. We knew it'd… change things." Things, meaning himself.

Castiel nodded, void of an adequate response.

Sam sighed, rubbing a hand over his face, his tone shifting, sounding both stronger and more defeated, "How's the search for Cain?"

Castiel paused at the shift in subject, trying to control the note of frustration in his tone, "My brethren are still searching."

The Winchester nodded, eyes narrowing slightly as they slid over Castiel, "And… your grace?"

He hesitated, then admitted with a degree of resignation, "It's… as well as can be expected."

Sam's expression twisted in soft concern, his words carrying a tinge of hope. "Is there any chance any of your grace is out there, somewhere?"

Castiel shook his head, raising his shoulders faintly, "Metatron… alluded to the possibility, but we can't trust a word from his mouth. It's not worth the risk, playing his game." The angel—a true disgrace to the name—had manipulated Castiel to ignite heaven's collapse. He'd wrought the deaths of countless angels, then toyed with them to establish himself as their god. He'd killed Dean, leading to his rebirth as a demon. No, he couldn't be trusted—every word that left his tongue was a tool designed to advance his ploys.

Sam nodded understanding, though the angel thought he glimpsed doubt and uncertainty lingering on the Winchester's face. His jaw tightened, but he didn't want to pursue the point. Castiel noticed the flick of his eyes toward his coat—toward the pocket where the flask lay hidden inside.

"Sam… you should focus on your recovery." Castiel noted carefully. Sam looked like he was drowning in the deep ocean, flailing madly just to keep his head above the tide. It'd be better for him to concentrate on his detoxification—worrying over Castiel's depleting grace and his brother's Mark with no solution in sight couldn't help.

"Yeah…" Sam agreed absently, finally tearing his gaze upward, meeting Castiel's with a haunted shadow. His eyes creased with a tentative, shame-touched plea, darting down to the hidden flask in gesture, "Cas, can you… can you get that away from me, please?" His voice, his face, his body were laden with so much weight. More than he deserved to carry.

Castiel rested a hand over his pocket, tilting his head in acknowledgement and accession. He started toward the door, pausing just before entering the hall to glance back. Sam didn't look up, his thumb still distantly kneading the site of the punctured vein. The angel didn't want to leave him alone in this state, but… it didn't exactly seem that Sam wanted the company, either.

"You're not alone, Sam." Castiel spoke quietly, each word measured and firm, "Dean and I will help see you through this."

It was a vow—and perhaps more than one of mere loyalty. Castiel would do everything in his power to ensure Sam got clean before… before the last vapor of his grace failed, and he drifted into the void. He'd fight to survive until his friend… his brother… was safe.

Sam managed a hazy nod, murmuring with the strength of a leaf in a hurricane, "Thanks, Cas."

Castiel cast a final glance over the man, his heart heavy with a myriad of thoughts and emotions, but not a word for one. At one point, such feelings would have seemed so foreign to the angel. Now, they seemed more common by the day. Resigned to silence, he inclined his head in a single nod and disappeared down the hall, his footsteps echoing softly with every step. As he strode into the shadows, his eyes skated to the ceiling in an old reflex, and he hoped from deep within his being that even a fallen angel's wordless prayer might fall upon the grace and mercy of his Father. For right now… heaven knew they needed it.