Silence hung heavy between them, Sam allowing his hand to linger against Cas's face, all too aware that he might be touching him for the very last time. He willed himself to go on, to explain – but he couldn't force the words out. And after a moment, Cas shifted back away from Sam a little on the bed, and Sam had to let his hand drop. A cold ache of loss settled in his chest as Cas looked away from him, eyes downcast, fumbling behind him on the bed for the discarded shirt.

"I – I'm sorry."

Sam's heart sank at the self-conscious sound of Cas's voice, as well as the fact that he was apologizing again. A dull ache settled deep in his chest; Cas had felt so safe with him, had been so open and unguarded for so long. But now, he seemed to be shutting in on himself, shame in every aspect of his demeanor… and Sam knew all too well that it wasn't Cas who should be ashamed.

It's all falling apart already… and I haven't even said a word yet…

"I – I've overstepped," Cas mumbled, his eyes carefully focused on his fingers as they struggled with the buttons of the oversized shirt. "I – didn't mean to…"

"No," Sam objected, reaching out to still Cas's hands, ducking his head a little to seek Cas's eyes. "No, Cas, you didn't."

Cas looked up at Sam, hurt and hope in equal measures in his eyes, and Sam wanted to pull his hands away, suddenly acutely aware of how inappropriate it was to be touching Cas right now with any sort of intimacy.

If he knew the truth… when he knows...

"Cas," Sam tried again, forcing himself to hold Cas's gaze, his words firm and emphatic, "you've done nothing wrong. All right? That's not it. You have – no idea how badly I'd love to just – to let you keep going, okay? But – I can't."

Cas stared at Sam, innocent and trusting and concerned, and Sam felt his face burning with shame, guilt making his stomach roll as Cas whispered, "Why not?"

"There's, um…" Sam swallowed hard, closing his eyes for a moment and struggling to steady his nerves. "… there's something you don't know, and… and you have to know. About – that night." He looked up at Cas again, forcing the words out. "At the cabin."

Cas's hands tensed under Sam's, his eyes wide and trapped for a moment before he looked away, shaking his head. His voice was low and unsteady. "I d-don't want to talk about – that night. There's – nothing I need to – to know…"

"Yes, there is," Sam insisted. "Cas… it's important. We – haven't told you everything…"

"Things are just beginning to get better." Cas's tone was imploring, quietly desperate. "Dean and I – we're speaking again, and I'm beginning to – to see a way to…" He swallowed slowly, his eyes reluctantly dragged back up to Sam's face, pleading. "I know enough, Sam. If there are – other things – details which might – make forgiveness less possible than it is now, then – I don't want to know them."

Sam nodded slowly, taking in Cas's words – and the depth of love and generosity, so sorely undeserved, that made it nearly impossible for Sam to keep control of his own emotions. Cas was offering Sam a way out – unconditional forgiveness, total trust, offered freely – without having any idea how grievously he'd been wronged, or even who he was actually offering it to. It would be so easy to just agree, just accept it and move on… and Sam desperately wanted to accept it.

But he couldn't.

"I get it," he replied when he trusted himself to speak again, his voice hushed and thick, his eyes burning. "But… you have to."

Cas pulled his hands away from Sam, frustration in his voice. "Why?"

Sam steeled himself for the sacrifice that came with the truth that was about to pass his lips. It was a necessary sacrifice, because what he was giving up had never really been his to begin with. He took a deep, steadying breath, then finally replied, pushing the words out in a rush of breath.

"Because… it's not about Dean."

Cas frowned, confused – but then his expression softened into sad acceptance. "Sam – I understand that – you both believed I was guilty. You both thought I was trying to destroy – everything. And – and that you'd both do it differently if you could. Beyond that – do any of the details really matter?" He shook his head, reaching out to gently squeeze Sam's hand. "No one ever tells anyone everything. I trust you, Sam." He was quiet for a moment, before adding simply, "I love you."

The ache in the back of Sam's throat intensified, and his eyes burned with unshed tears, his voice thick and hushed as he struggled for control, fighting to get the words out. "That's – exactly the problem, Cas," he admitted, hesitating before finishing in a choked whisper. "You shouldn't."

Sam ventured a glance up at Cas's face, just in time to watch it fall with hurt and disappointment; that was clearly not the response he'd been hoping for. And Sam knew better than to expect him to understand, when this was all done, that it was Sam's returned love for him that left him no choice but to do this, to come clean and shatter everything that had been building between them these past weeks.

"I do… want this, Cas," Sam tried to explain. "I want – us, but… before that can ever happen, you – you have to know some things, and – and once you know them…" Sam looked down at the bedspread between them, unable to bring himself to pull his hand away from the warmth of Cas's touch – too aware that it might be the last time he'd ever feel it. "… once you know them…" He swallowed hard. "… you won't, anymore. Love me. You'll – you'll want to get as far away from me as you can."

The hurt in Cas's eyes faded slowly into confusion, and then dread, and he shook his head, pulling his hand away and shifting back a little on the mattress. "Then… I don't want you to tell me," he replied. "I – don't want to know…"

Sam's heart sank. "Cas…"

"Please don't, Sam…"

There was a note of frantic desperation in Cas's voice as he rose to his feet, backing away until he stood near the foot of the bed, and Sam's heart lurched with the sudden panicked certainty that Cas was about to flee the room, that he was about to miss this chance – and if he let it slip away, this time, Sam knew that there was no way he'd be able to find the strength to try again. He rose with Cas, reaching out and catching his arms.

"Don't go, Cas," he pleaded urgently. "I – I have to say this."

"No, you don't." Cas looked up at him, frantic. "You don't have to. You said you wanted… us, together, right? So let's just go back to that. Please, you don't have to say anything, please don't say anything, Sam…" Cas leaned in as if to try to kiss Sam again, but Sam held him back, closing his eyes to shut out the desperation in the angel's eyes, turning his head away. A moment later, he felt Cas's face fall against his shoulder, Cas's hands at his waist, holding on tight… soft, defeated words muffled against Sam's shirt.

"Sam… don't. Please don't."

The swelling ache in Sam's chest was almost more than he could bear. Cas knew that there was something that had been kept from him, something that would change the way he saw Sam – and here he was literally begging Sam to keep quiet, to keep it to himself, to keep lying to him. And God help him, that was all Sam wanted to do. Sam could keep his mouth shut, and things could go on just like Cas was begging him for, just as he'd almost let them a few moments before, sweet and warm and intimate, and Cas never had to know, ever… but…

Sam would know.

And Dean would know. And Dean would never forgive Sam for allowing Cas to blindly adore him while struggling every day just to find a way to love Dean again, at all. And Sam would never forgive himself, every time Cas gave himself to Sam, every time he was allowed a glimpse of those breathtaking wings – for the fresh violation Cas wouldn't even know was happening.

Sam knew that if he didn't do this now, if he gave in and surrendered to Cas's pleas and his own desires, he'd never find the strength to speak again. Cas was clinging to him, hands tight in Sam's shirt. Sam wasn't sure he could dislodge him if he tried – and he didn't want to try. Eyes burning, Sam swallowed hard past the painful knot in his throat, as he slid one hand gently up Cas's arm to his shoulder, stopping when it was cupping the back of Cas's neck. Cas was still shaking his head, a silent plea, and Sam slid his free arm around Cas's waist, lowering his head so that his cheek rested against the top of Cas's head, momentarily stilling him.

"That night…" he forced himself to begin in a choked whisper, ignoring Cas's soft little whimper of protest and pressing on. "… at the cabin… we didn't know what to do, Cas. We were… running out of options, and we thought the whole world was going down if he couldn't make you talk, and you wouldn't talk, and… I found this book…"

"Don't, Sam, don't, don't…"

The words were a small, despairing sob, and Cas's body was shaking in Sam's arms now, but Sam didn't let himself stop, didn't let himself focus on the pain the truth would cause. He kept his eyes closed, even as tears escaped in hot tracks down his face, because he knew if he looked at Cas right now he might not be able to go on.

"It had a spell in it… the… the Unspeakable…"

Cas flinched away from him, but Sam held on, desperate to finish this now that he'd started, his words tumbling over each other in a mad rush to escape, his voice rising in speed and volume and thick with tears.

"I found it, Cas… I gave it to Dean. I – I told him to use it, if he had to, to – to save the world. Dean – he didn't think he could do it, and I – told him if – if we had to…" Sam's voice broke, and he struggled to maintain his composure, as Cas shook his head against Sam again in silent denial. "We – I thought we were saving the world, Cas." He spoke with a pleading fervency, desperate to somehow make Cas understand the reasons that had felt so important at the cabin – that now seemed so futile, so worthless. "That… had to come first, right? Over and over we keep putting each other first, and every time the world gets a little bit shittier, a little bit more fucked up, and this time we just couldn't do that anymore, you know? We had to save the world…"

Sam's voice broke, and he couldn't go on. He wanted to be sick – because it all sounded so hollow, like worthless excuses to somehow justify the absolute worst thing he and his brother had ever done.

Cas was still and silent in Sam's arms, his body tense but unmoving, and Sam couldn't bring himself to open his eyes. He felt everything inside him breaking apart, felt the closeness and warmth that had built between him and Cas over the past few weeks slipping like sand through his fingers. He sank onto the end of the bed, his hands sliding down and clinging to Cas's clenched fists, covering them like a prayer as he bowed his head, tears streaming.

"I should have saved you, Cas," Sam sobbed out, wretched and ashamed. "I should have saved you."

Everything was silent and still, the only sound the harsh, choked sound of his own sobs – and suddenly Sam lost his balance, shaking hands grasping empty air where Cas had been. Sam looked up, blinking, to see Cas across the room, out of his reach, glaring at him through eyes that glittered with angry tears.

"Why would you do this?" Cas demanded.

Sam lowered his head into his hand, shaking it in despair. "I – I thought we had to. I was wrong, Cas…"

"Why would you do this now?"

Sam blinked, taken aback, struggling to process the unexpected question. "What?"

Cas looked away, his jaw clenched. "For weeks," he clarified in a voice that was barely under his control. "You lied to me. And… you made me trust you, and feel things that I – I showed you… and you let me…" Cas looked up at Sam again, wounded horror in his eyes. "How could you keep this from me?" When Sam couldn't find an answer, Cas lowered his eyes, his voice soft and despairing. "How could you tell me, now?"

Sam was confused, utterly at a loss as to how to answer that question. This conversation… wasn't going at all how he'd expected that it would. Cas almost seemed more upset about being told the truth now, than about being lied to in the first place. The shock, the outrage that Sam had anticipated – both were far more subdued than he'd imagined; there was more of a quiet, sorrowful resignation in Cas's reaction.

And suddenly, the truth hit Sam with the force of a speeding train, rocking him back on his heels and leaving him speechless, his heart sinking with slow, seeping comprehension.

He knew.

Sam's mind went back to the cabin, and what had actually happened there – not just the brutality and trauma, but the sequence of events – and wondered why he'd never thought to question it before. Cas had known Sam was there, with Dean, when they'd cast Jacob's call and trapped him in the cabin. Sam had physically held him down while Dean drugged him so that they could remove the tablet from his body. Just because Sam wasn't actually in the basement with Dean was no reason for Cas to assume that Sam had left the premises entirely while he was being tortured. Cas had screamed and cried out for rescue while Dean had brutalized him.

Which means… he had to have believed… there was someone there to hear him.

He knew. Not all of it, not every detail, but… on some level… he knew.

"Cas… I'm sorry," Sam tried, shaking his head, well aware his efforts were weak, meaningless. "I had to tell you. It… it wasn't right, lying to you all this time, and…"

"And now you're so concerned with doing what's right. Convenient." Cas's voice was hard again, bitter words spit at Sam, and he flinched a little before looking up to meet Cas's accusing gaze – and there it was… the fury of betrayal that Sam had prepared himself to accept. "Like how you and Dean decided to change your methods of doing things… to put the world first… the very first time that the sacrifice wasn't one of you."

Sam reeled, Cas's words like a slap. "Cas… no…"

"Yes." Cas's tone was disgusted, emphatic. "Dean wouldn't have done it if it'd been you instead of me. And if it'd been Dean keeping the secret that could end the world, and you found a spell that could save the world by utterly destroying him until he was too shattered to hold his secrets any longer… you'd have burned that spell rather than hand it over to anyone."

Sam tried to find the words to argue, but there were none. Cas spoke the truth – and as Cas watched Sam's reaction, his shoulders fell with defeat, and he looked away.

"I would have, too," he admitted in a voice gone quiet, empty with exhaustion. He looked up at Sam with desolate eyes. "I was foolish," he stated softly. "To trust you so completely. Knowing that… just like Dean, you'd never… never choose…"

Cas couldn't finish, his voice breaking over the last word, and his head bowed, eyes closed – but he didn't have to. It was all too clear – and it smote Sam's heart with guilt and regret. He stood up, taking a cautious step toward the angel, now silent and still, across the room.

"Cas… you're wrong," Sam attempted gently. "Okay, you were right about… before, but… we've learned from this, okay? And – things are different now. It's not about… me choosing you or Dean… or Dean choosing you or me. It's… the three of us, in this together. At least… that's how we – how I – want it to be." Sam swallowed hard, taking another step, though Cas kept his eyes downcast, offering him no encouragement or warning. "What you said," Sam ventured, uncertain but desperate to reach Cas, just wondering at the fact that the angel was still there, at all, in the room with him. "How – how you feel… Cas… I feel it, too. You have to know that, no matter how many horrible mistakes I've made, no matter how I've hurt you, I – I do. I love…"

"Don't."

Cas's voice was low like thunder, his eyes blazing as he raised them to meet Sam's in an arresting gaze that made Sam's stomach drop with alarm. As Cas spoke, the lights in the room began to flicker, a low hum rising around them that was just the barest echo of Cas's true voice – and though Sam couldn't tell what that voice was saying, the fury of it – Cas's pain and rage and betrayal too overwhelming for human words – filled the room, and Sam froze, falling silent, barely daring to breathe, let alone take another step.

"Don't," Cas repeated, voice quieter but no less commanding, holding Sam's gaze. He was silent for a moment, before continuing, a soft and certain condemnation. "Every word you've said… every single time you've touched me… has been a lie."

Sam's eyes burned with tears, his heart sinking with despair. He knew he wasn't going to be able to fix this, didn't deserve the chance to – and the loss of the tenderness and intimacy that'd existed between them mere moments earlier pulled at him, making him long to go to Cas, to hold onto him, to desperately try to claim him back.

He didn't dare.

"Cas…" he choked out, lowering his head, struggling to find words. "I'm so… so sorry…"

But the words died in his throat when he looked up again – and saw that he was staring at empty space where the angel had stood. The silence, the stillness that filled the room in his wake was such a crushing weight in Sam's chest that he suddenly found it difficult to breathe. He staggered back a step or two, his mind reeling as it began to catch up with the finality of what had just happened. And as he sank down onto the floor at the foot of his bed, he could only gasp out Cas's name through his tears – a broken and despairing prayer that he already knew would go unanswered.