Sam watched while trying to look as if he wasn't watching, as Dean stopped at the ratty sofa and set down his duffel bag, opening it up and rummaging through it. Sam swallowed, making himself look away. Finally, Dean zipped the bag closed again, shouldering it before he approached Sam with one hand extended.

"You'd better hold onto this, too," Dean said, his voice low and unsettlingly calm. "As long as you're keeping all the deadly weapons for angels out of my reach."

Sam looked down at Dean's outstretched hand, understanding dawning when he saw the vial of holy oil there. He took it and set it on the table beside his laptop. "It's not, though," he pointed out. "Not with his grace restrained."

Sam wasn't really sure why he'd felt the need to clarify that. Maybe even in the midst of this utterly fucked up situation, he couldn't stop focusing on the details, couldn't stop being a "nerd" as Dean would have pointed out if he wasn't so thoroughly, horrifyingly focused at the moment.

Maybe he was just stalling, trying to delay Dean in getting to his intended destination.

It worked, if only for a minute.

"Huh?" Dean frowned.

"The holy oil works because it responds to an angel's grace," Sam explained. "With his grace repressed like it is right now, the holy oil can't kill him. The information I found on Jacob's Call says it isn't lethal as long as the bond is in place. The only thing that can kill an angel under the bond is an angel blade – and only in the hand of the person he's bound to." Sam paused, a nervous huff of humorless laughter escaping his lips as he added, "It'd still hurt like hell, though."

Dean nodded absently, distracted, as he headed toward the stairs. Sam wanted so badly to call him back that when Dean stopped, Sam felt a tremendous sense of relief. Maybe he'd just thought of something – something that could keep them from having to do this.

But when Dean turned, his expression was still carefully blank as he returned to the table. He picked up the vial, turning it over in his hand, looking down at it speculatively for a long moment. Finally, he tucked it into his pocket. His flat, expressionless words, without hesitation or a shred of emotion, sent a chill down Sam's spine.

"Guess this might come in handy, then, after all."

Sam didn't know what to say. His mouth was dry, his heart racing, and he felt sick to his stomach. Dean looked up at him with dead, cold eyes, seemingly oblivious to his reaction. Sam hoped that meant he was hiding his horror well.

"What was that thing, earlier? The other thing? The one you didn't want to tell me?"

Sam frowned, shaking his head in confusion.

"The thing you said we couldn't do to Cas," Dean clarified, his eyes hard, his tone slightly impatient. "What was it?"

Sam's stomach clenched as he remembered. "Dean…" he whispered, his brother's name coming out weak and choked.

"Come on, Sam."

Sam swallowed hard. "It – it's bad, Dean…"

"Tell me."

As Sam hesitated, the mental image of the classroom of children murdered by angels filled his mind. The memory of how it'd felt to see Dean's hands stained red when he'd walked in the door – how it'd felt to hear his explanation for how that blood had gotten there.

Whatever we have to do… we have to do it.

"It's his wings," Sam blurted out, before he could think himself out of it. "They're – apparently the most sensitive part of an angel's body. Where they're – most vulnerable."

Dean frowned. "Yeah, that's great, Sam. But we can't see them…"

"Right. We only see the shadow they cast, or the scorch marks when they've been burned away. But… there's a spell." Sam was quiet, resigned. "It's in one of the books we brought from the library. It can make an angel's wings… visible to humans. Tangible. Allow humans to – to touch them."

Dean considered that for a moment, then nodded slowly. "Good. That's what we need, then, right? We need to break him as fast as possible…"

"I don't know, Dean." Sam hesitated, finding it difficult to maintain eye contact with his brother at the moment, unsettled by the unnaturally placid expression on Dean's face as he casually discussed torturing and breaking their closest friend and ally. "This book is… pretty ancient, and… it seems like some pretty heavy mojo to be working."

"Yeah. And we're in a pretty heavy situation," Dean pointed out. "World's ending, Sam. Unless we stop it. Fast."

Sam raised a hand to rub at the back of his neck, frowning and trying to find the words to make Dean understand his misgivings. "It's just – the book says the spell was carefully guarded by the angels for centuries, because – I don't know, the writers weren't clear on the details, but the book refers to it as… well, it literally translates to… 'the unspeakable'. As in, it was so secret, there aren't even Enochian words for the spell, because the angels were forbidden to even speak of it, even amongst themselves. The guys who recorded the information believed that, to the angels, it's like – the worst thing that can possibly be done to them." Sam watched Dean's face closely for any sign of hesitation, increasingly unsettled when he found none.

"Well, yeah," Dean reasoned with a harsh little scoffing sound that, strangely, almost made Sam flinch. "Really convenient that the most vulnerable parts of their bodies are always protected from humans. Guess they would want to keep that secret."

"I don't know, Dean. It just – it seems like a really drastic step to take…"

"We're miles past 'drastic'," Dean countered, his tone flat, as he held out his hand. "Give me the book. Show me the spell." He frowned. "What language is it in, anyway?"

"The early Men of Letters translated it into Latin. And the words are – pretty simple, but… this is blood magic, Dean. I mean – if you think we really need to, I'll…"

"If I think we really need to, I'll do it," Dean snapped, impatient. "We are officially out of options, all right? We don't have a choice."

"I know." Sam's voice was quiet, his eyes carefully focused on the book as he paged through it, a little slower than he could have, seeking the correct page. "It's just… the way the book makes it sound… if – if we do something like that – no matter how this ends…" He looked up as he found the page, meeting Dean's blank eyes with his own, worry gnawing at his stomach. "… Cas is never going to want anything to do with either of us again."

Dean looked away for a moment, his tone bleak and heavy. "Pretty sure that's gonna be true either way," he said. He was quiet for a moment, considering. Then, to Sam's immense relief, he softened just a little, meeting Sam's eyes again with sympathy. "Look, Sammy," he sighed. "I'll only use it if I have to, all right? It's just – just in case. Just – show me?"

Sam bit the corner of his lip, hesitating just a moment before nodding and turning the book around, pointing out the passage to his brother. Dean read over the Latin under his breath for a moment before nodding and taking the book, making Sam cringe when he folded the page down before closing it and tucking it into his bag.

"It's not like I'm actually gonna have to use it, anyway," Dean remarked, his tone flat and cold again. He looked up at Sam again, and for just a moment, Sam thought he caught a glimpse behind the mask, to the sheer misery in his brother's eyes. Then it was gone, shuttered behind a cold smile, as Dean concluded softly, "He's not gonna last that long."

When Dean reached the bottom of the stairs, Cas was lying on his side, curled protectively around his injury; but he looked up as Dean neared him, eyes wide and wary, watching Dean as he set his duffel bag down on the table, opened it, and calmly began laying out its contents on the table, where Cas could clearly see them.

Dean didn't speak to Cas or turn toward him, but he hazarded a glance out of the corner of his eye as Cas shakily dragged himself up on one arm.

"Dean." Cas's voice was hoarse and weak, and he winced as he struggled to swallow. Dean picked up a knife in one hand, and the half-full whiskey bottle he'd taken from the liquor store in the other, and turned to face Cas without looking at him. "Please… can we talk about this? What's happening? I know you – you think I'm… causing it, and I'm not, but… but someone is, and… and perhaps… if you tell me what you're seeing… out there… we can… figure it…"

Cas's words trailed off as Dean reached him and knelt down on the floor facing him. He tried to pull away, but his efforts were useless as Dean reached behind him with the same hand that held the knife, grabbing a bit of his hair and yanking his head back. Cas's eyes were wide, frantically trying to follow Dean's hand – or more accurately, Dean figured, the knife – before he gave up and fearfully met Dean's eyes.

Dean smiled, keeping his voice quiet and deceptively light as he observed, "You're stalling."

With his other hand, he raised the whiskey bottle and took a long drink. Then he raised it again and poured a mouthful past Cas's parted lips.

Cas coughed and choked, trying to pull his head away, but Dean just held him still, forcing his head to stay back until the last of the whiskey had gone down. While he patiently waited, Dean set down the bottle, a low laugh escaping his lips.

"Oh, Cas," he said softly, shaking his head, something like affection, but sadder, darker, in his voice. "Take away one little thing… your grace… and you go from guzzling down a whole liquor store to choking on one drink."

Cas flinched slightly, looking away, and Dean knew his words had gotten their message across – a pointed reminder of the angel's current state of helplessness. As he tilted his hand, allowing Cas's head to fall forward without letting go of his hair, Dean reached back to take the knife with his free hand, bringing it around and resting the blade against Cas's chest. He tapped it lightly a couple of times, watching Cas's reactions closely with a faintly mocking smile on his face.

"Better?" he asked.

Cas's voice was only slightly less hoarse, his wary eyes on the blade, when he managed to reply, "Not… not really."

Dean laughed.

Cas's eyes were pleading, wide with rising fear, and Dean could tell that his behavior was having its desired effect. "Dean… please talk to me. Please, just…"

"No, Cas," Dean cut him off, pressing the blade up under his chin and silencing him as Cas bit down on his lower lip and closed his eyes in a pitiful attempt to control his reaction. Dean kept his voice soft and measured, perfectly controlled, as he continued, "You are going to talk to me."

"Sam." Cas barely managed to gasp out the word as Dean trailed the blade slowly down Cas's neck to his shoulder, pushing his shirt to the side with it. Dean froze, ice in his veins as his eyes locked with Cas's again. There was a trace of dread in Cas's eyes, as if he knew it was possible he had just made a terrible miscalculation, but he swallowed hard and continued, "I – I want to talk to Sam. Where is he?"

Dean wasn't aware of his hand tightening in Cas's hair, of the blade pressing tighter against his skin, until Cas winced, drawing in a sharp, shaky breath. With an effort Dean eased his grip a fraction, resumed the blade's idling path down Cas's arm, using the motion to slide his shirt back and off to hang around his wrist.

"You don't need to talk to Sam," Dean replied, tracing the knife across Cas's stomach, smiling a little as Cas flinched away from the touch of the blade, but couldn't get far with Dean holding him in place. "Sam has nothing to do with this."

"He… he wouldn't approve of what you're doing," Cas tried again, breathless, and Dean heard the slightly higher pitch of his voice, the telltale sign of his rising panic. "He said…"

"Maybe he wouldn't," Dean cut him off again, watching the knife as it pushed Cas's other sleeve down, leaving his shirt gathered around his wrists and further restricting his movement, his torso bare and vulnerable to Dean's blade. "But he's not here right now, is he?" Dean used the tip of the blade to tug, just barely, against the lowest of the stitches on Cas's chest, and the angel bit back a frightened cry. Dean smiled. "This is between you, and me," he concluded. "And you're gonna tell me how to save the world."

Cas said a lot of things over the next hour, as Dean employed his blade as creatively as he could manage on this plane – but none of them were what Dean needed to hear. He knew he couldn't kill Cas, not without the angel blade – but he also knew from his own painful experience that it was possible to do enough damage to make even an immortal subject utterly incapable of offering any sort of response. It was a fine line – inflicting enough pain to be persuasive, yet without that pain being so overwhelming that it made the whole exercise pointless.

An hour and a half in, and Cas was a trembling, bloodied wreck – but he still hadn't yielded the information Dean needed. He still insisted that he was innocent, that someone else was causing the disasters, that Dean was being lied to. Dean knew, he assured Cas. He was being lied to, all right. But not for much longer.

Another hour in, and Cas stopped trying to defend himself. He became silent and still, unresisting… no more pleading or arguing. His shaking, flinching reaction to Dean's blade had become a constant fine tremor, and he watched Dean's hands with blank, glossy eyes that seemed resigned to the suffering – but no longer particularly moved by it.

So, Dean brought out the vial of holy oil.

And – that got a reaction.

As Dean trickled a little of the oil onto Cas's shoulder, Cas jerked away from it with a gasp, staring up at Dean with horrified disbelief.

"Dean," he rasped out, his voice hoarse from his repeated attempts at pleading his case. "You can't. You'll kill me."

Dean didn't respond, just took out his lighter and flipped it open, staring at the tiny flame with a slight smile on his lips.

"This is foolish," Cas snapped, his voice shaky but stronger than Dean had heard it in hours. "I can't tell you anything if I'm dead!"

Dean looked up at him then, latching onto the slight slip – the first even minor success he'd had during this whole encounter. His smile widened slightly as he closed the remaining distance between them, holding the lighter a few scant inches away from Cas's shoulder, glistening with the oil Dean had spilled there.

"Oh, so there is something to tell, then," Dean remarked with a note of triumph in his voice. "Thought so."

Cas's face fell with dismay as he seemed to realize what he'd said, and he shook his head slowly, his eyes shining in the light from the flame as he watched it. "Dean," he whispered. "No… no, that's not…"

Dean kept the lighter where Cas could see it as he moved to stand behind him, then abruptly grabbed him by the throat, cutting off his protests and any attempts to pull away, as he touched the lighter to the oil, and it erupted in flame. Immediately Dean stepped back, not wanting to get caught by the flame himself – and a moment later, Cas let out a choked cry of anguish, fighting desperately against his chains, struggling to find a way to put out the flame that burned his skin. Of course, there was nothing he could do. He couldn't reach it with his hands, had nothing to press it against to smother it. All he could do was helplessly let it burn.

Dean watched impassively for a few moments, before taking a cloth from the table beside them and pressing the rough fabric against Cas's scorched skin, deliberately dragging it just a little as he pulled it away. Cas was shuddering, gasping for breath, a low moan of agony escaping his lips as Dean crouched behind him, his hand at Cas's throat again, pulling him back against Dean's chest. Cas shook his head, wordlessly pleading, as Dean held the vial of oil in front of him, tilted as if to pour out more, this time on Cas's wounded chest.

"I'll give you two seconds to start talking," Dean said softly in Cas's ear. "Or you're gonna get it again."

He released his grip on Cas's throat as he poured the oil out, and Cas's breath quickened with panic, as he pleaded frantically, "Dean, no… don't…"

Dean lit the oil – and the angel let out a scream, back arching as the flame licked at his skin, and he struggled uselessly to escape it.

A mere fifteen minutes later, Cas lay unconscious on the floor, passed out from the pain. Dean sat in the wooden chair next to the table, his head in one hand as he stared at the tools of his trade that he'd already put to use, with no effect – and then at the book that lay there beside them.

He'd tried everything he could think of, every trick Alastair had taught him for extracting a confession – not that the confession itself had ever really mattered in Hell. Whenever they'd gotten whatever "information" they claimed to want, they'd simply start all over again with a new question. Or not bother with the question at all, but just carry on with the pain. It was simply a point of amusement for Alastair, a proof of his skill, that he could convince anyone to admit to anything.

And it was a skill that Dean had mastered, too, eventually.

So why the hell am I getting nowhere? Dean brought his hand down angrily on the table, cursing under his breath. How is he still holding out?

He had gone so far already – crossed so many lines he'd sworn he never would again – and with no success. They had only a few short hours left before it would be too late, if it wasn't too late already – and Dean was running out of options, and ideas. He lowered his head into both his hands, closing his eyes as he drew in a deep, shaky breath, and let it out slowly.

The sound of Cas's panicked, agonized screams filled his head, and he didn't let himself even think about his brother, upstairs – the things he'd been hearing, the things he must be thinking right now. Sam had told him to do whatever he had to do, and that's what he was doing. He didn't have a choice.

He couldn't bring himself to look at his one-time friend – never again, no matter how this ends – bloodied and scorched on the floor at his feet.

Dean opened his eyes, looking at the book again. He picked it up and turned to the page he'd marked, laying it open on the table in front of him. It was a pretty simple spell, to be spoken of in such ominous terms by the Men of Letters. A few easy Latin words, spoken over some blood from the angel in question, drawn into a simple sigil on the floor.

It's the worst thing you can do to an angel… Sam had said.

But it's the only option we've got left.

Dean swallowed hard, finally forcing himself to turn his gaze toward Cas, who was just beginning to shift on the floor with an unconscious whimper of pain. Dean didn't let himself look away, sitting up and squaring his shoulders, schooling his face into the impassive mask he knew he had to wear, knew he had to present to Cas, because if he let it slip – if he let a trace of how much this was killing him out in his eyes, if he even let himself feel it for a moment – Cas would see it.

Cas would see it, and he would know – and any advantage they currently had would be lost.

Dean watched, trying to distance himself from what and who he was watching, trying to pretend that it was just another random soul on his rack, just another fool who'd brought this on himself, with his own evil deeds or foolish dealings with demons. And in a way, that was Cas, wasn't it?

He brought it on himself… he's the one killing the world…

Cas looked up at Dean, blue eyes blinking in confusion… and Dean watched as it all slid back into place, and Cas remembered where he was, and why. Fear replaced confusion, in the instant before Cas looked away, his eyes on the floor instead of Dean's face.

He remembered that, too – and the rush of pleasure that usually accompanied the moment when he knew his victim held a true and almost reverent dread of him – that they knew the power he held over them, and didn't dare to risk his anger.

Seeing it on Cas's face… all Dean felt was sick.

"Dean," Cas said, his voice careful and quiet, betrayed by a slight tremor behind the words. "Please. You – you have to see. This is pointless."

Dean glanced down at the book again, before rising to his feet. Cas glanced up anxiously, accidentally meeting his eyes for just an instant – and the angel visibly wilted, drawing back the pitiful amount that the chains and his injuries would allow him. He flinched as Dean crouched down in front of him, placing a firm but gentle hand at the back of his neck. But when no pain immediately followed the gesture, Cas looked up at Dean again hesitantly, questioning. Dean nodded slowly, glancing down at the floor for a moment before meeting Cas's eyes.

"I know," he said simply.

Then he reached down and dipped his hand into the pooled blood on the floor, where his knife had spilled it. Cas watched him with a frown of confusion, as Dean moved a little ways away and crouched down on the floor.

"Dean? What… what are you…?"

Dean ignored Cas's quiet, uncertain words, dipping a finger into the pooled blood in his palm and painting the required sigil on the floor. When it was finished, he wiped his hands off on the same rag he'd used to put out the flames, then picked up the book.

"Dean… wait…"

As Dean began to speak the Latin words over the blood sigil, Cas abruptly went very still, very tense. He jerked against his bonds, his eyes darting back and downward as if he could see over his own shoulder, as a sharp, startled cry left his lips.

"Dean… no!" Cas cried out. "Wait, no! Don't do this! Don't!"

Dean ignored him, continuing the chant as Cas writhed and fought against the chains, desperate to free himself, as if struggling against some unseen attack, and Dean knew that the spell must be working. Dean almost flinched himself as Cas lunged toward him abruptly, as if he could somehow stop Dean from finishing the spell, despite his helpless state, and Dean didn't know whether to laugh or cry. It was so desperate, and so pathetic, and he wondered why this spell was so very terrible, anyway, and his voice shook just slightly over the last few words… but he didn't stop.

"Dean, no!" Cas sobbed out, his voice raised and rapid with panic. "Please, you can't do this! I know you, Dean, and I know you think you have to, but you can't do this! This is an abomination, and you are the righteous man, and I know you can't do this, please…"

Dean looked up at last, the Latin fully spoken. He swallowed with difficulty, not sure why he felt this hesitation, this something inside him that was quailing under the force of Cas's desperation, and a near palpable sense of something electric and powerful filling the room. For a moment he considered not finishing the ritual. He could find another way.

Except, there was no other way. There was no more time.

Just Sam's voice, echoing in his mind, "Whatever we have to do…"

"You were right before, Cas," Dean said, his voice low and trembling slightly as he held his hand, still coated in Cas's blood, dripping over the sigil. "Hell broke your 'righteous man'." He paused, glancing down at the sigil, increasingly aware of the crackling, electric power surging in the room. "Now – now, I can do whatever I have to do."

Before he could hesitate any further, before his nerves could get the better of him, Dean brought his hand down into the center of the sigil, as Cas let out an anguished, pleading cry. A bright flash of light flooded the room, along with a shockwave of energy that knocked Dean off his feet and onto his back on the floor. The unsettling, ear-piercing sound of angels' voices faded in, and then out again swiftly, as the light faded away – leaving only a massive wall of black, large enough to block out the light from the tiny basement windows… and the soft rustling of angel's wings.