A/N: This was inspired by a beautiful cosplay gif story by the very talented asktheboywholived on tumblr - I wrote this with their direct blessing.

"Pair up and spread out. Watch each other's backs, and be damn careful what you touch. Merlin only knows what could be in here."

With Moody's less-than-reassuring instructions ringing in their ears, Sirius and Remus made their way down to the basement of the old manor, as their friends peeled off pair by pair to search the other floors. It wasn't really the most pleasant building - in fact, both of them were pretty sure it should be trained Curse-Breakers dealing with the place, not people barely out of adolescence… but the Order just had to make do. Things were getting a bit desperate.

Most of the building reminded Sirius a bit too much of where he'd grown up; he couldn't help getting a bit fidgety, half-expecting his parents to suddenly emerge from a doorway.

The cellar, on the other hand, was large, but almost boringly normal - somewhat anticlimactic, they agreed after a few minutes of searching. Not a single trace of Dark magic was anywhere to be found. "I don't know, Pads," Remus said as they reached the far wall without incident. "Maybe Moody's just got it wrong about this place."

Sirius looked over… and past him, with a mischievous grin. "Oh, I don't know," he said brightly "That door you're leaning on might argue. If doors could argue, I mean."

Remus rolled his eyes and turned to take a look. It was certainly well-hidden; Sirius had only spotted it due to the light from his wand falling on it at the right angle to outline the cracks.

Apparently the concealment was the best security the builder had felt necessary to include, as a simple "Alohomora," was enough to make it swing open with a faint creak. The two young men exchanged an amused look, and Remus, wand at the ready, stepped in.

Nothing about the little room he entered seemed particularly sinister. "I don't think there's anything in here," he observed as he moved further in, though his voice seemed to echo oddly, as did the scrape of Sirius's boots on the dusty floor as he followed.

"There must be something." Sirius was almost disappointed; a secret room without the decency to even have anything interesting in it?

Then an angry red glow suddenly bathed the room.

The last thing Remus remembered was a blow to his back, as though a spell had struck him.

Sirius's last memory was of Remus turning, wand arm rising, before everything went black.

When Remus woke again, it was to find himself slumped in a chair, held up by the tight straps around his arms and chest. His back still ached from whatever he'd been hit with, and he felt slightly dizzy. He raised his head, trying to get a sense of his surroundings, and nearly jumped at the sight of Sirius, lounging in another chair a few feet away, watching him neutrally.

"S-Sirius?" he croaked, tugging against the straps weakly. "What…?"

The silence stretched out, and Remus stared uncomprehendingly for a moment. Why would Sirius just sit there and watch him struggle, when they were clearly in trouble? Unless the trouble wasn't going to affect him… Comprehension and dawning horror broke over Remus in one horrible moment as he realised just who had to have cursed him from behind.

"You're the spy." His voice sounded odd - numb, distant, detached. As if it was someone else speaking, while he just watched the world stop making any sense at all.

The handsome young man's face broke into a gleeful smile. "Spot on, Moons," he said brightly. "Took you a minute."

"Let me go." Even as he said it he knew it sounded far too much like pleading.

Sirius cocked his head as he eyed his captive with a look of amusement, almost as if he was surveying a particularly good prank. "Nah… I think I like seeing you like this." He straightened up in his seat, with a flicker of spiteful humour. "Tied down… caged, like the creature you are."

The verbal blow hit harder than any physical one could have, and Remus yanked against his restraints, stung to the bone. "Y-you - how could y-"

"Don't worry," Sirius cut him off lazily. "It'll be over soon, Remus."

He couldn't have made it any plainer. I'm going to watch you die. Stunned, heartbroken and reeling at the betrayal, Remus gave up struggling and slumped back as tears rolled silently down his face.

The sight seemed to intrigue Sirius. "Never seen you cry before, Moony…" he murmured, with the air of a scientist discovering a mildly interesting new fact. "You were always so stoic. Heartless git."

The tears were coming freely now. Humiliation at his own weakness, guilt, devastation, all combined to keep them flowing. "Pads… why are you doing this?" he choked through the lump that was beginning to force its way up his throat. Why twist the knife? You've got me here, just end it.

Sirius's laughter, callous and full of malicious delight, echoed around the room. He gazed at Remus thoughtfully for a moment, then crossed the room, leaning down in a way that made Remus's heart beat faster despite the horror of the situation. But instead of the awaited - or dreaded - kiss, he felt Sirius's lips brush his cheek, and heard the chuckle in his voice as he murmured, "Do I need a reason to put down a monster?" Remus winced as though he'd been smacked, and Sirius leaned back, apparently gauging the effect of his words.

It was too much. Crying in earnest now, Remus looked back up and tried to speak through the racking sobs. "I thought… that you…" How could he have thought it? How could he have believed for so long that there was hope?

Sirius's lips curled into a smirk. "What?"

"I thought you…" The words died on his lips at Sirius's expectant, knowing look, and he turned away.

I thought you loved me.

Sirius leaned forward, his eyes cold as ice, and Remus felt hot breath on his cheek. "You thought wrong."

The shout of panic had echoed up through the manor and drawn everyone within earshot to the cellar. It took the combined efforts of Moody, Kingsley and Frank to prevent them all from piling in.

"Calm down - just calm - Jones, don't make me do something you'll regret!"

Hestia fell back, glaring, but James, overwhelmed by sheer panic, immediately tried to wedge himself into the gap and ran straight into Kingsley's arm.

"Why are you just standing there? They're in trouble! PADS! MOONY!"

"Shut up, you idiot!" Moody slammed him against a wall, knocking the breath out of him long enough to make him listen. "Screaming your head off'll just bring more trouble! Now shut your mouth for a moment!" He glared at the rest of the group, who had fallen silent. "Pettigrew, Longbottom, mind this door. Kingsley, Potter, with me. We'll sort this out. The rest of you, get back to work. I want us out of here before dawn."

It was a testament to their trust in him, or perhaps their fear of him, that the Order obeyed without a single murmur.

Peter was all but quaking in his boots as he was left with Frank. "We'll be back before you know it," James said, squeezing his friend on the shoulder. "You know those two, they're always running into trouble. They'll be fine."

The weak smile and nod he got in return were nowhere near enough to keep his heart from sinking as he headed into the extensive cellar with the two senior Aurors. If Sirius and Remus were in trouble, why weren't they at least shouting for help?

Kingsley was the one to spot and point out the half-open secret door, and had to prevent James from rushing straight in. "No knowing what's happened," he said gently. "Look before you leap."

Moody nudged the door open fully with the end of his stick, and James let out a strangled groan.

Remus and Sirius lay sprawled on the floor, pale and motionless, as though they'd dropped where they stood. A faint, eerie red glow lit the scene, though it seemed to outline things more than illuminate them.

"They - they're not -"

"They're breathing," Moody growled. "But they're out cold. Don't go in -" He flung his arm out as James tried to do just that. "Nobody in there but them. There's a curse been laid on the room itself."

"…Can we get them out?" James begged. The sight was ripping him apart.

"Don't know yet. Give us a bit to study it, see if we can work out what exactly we're dealing with."

James nodded and backed off, though a choked sob stopped him from going far. Peering into the room from a safe distance, he saw the glint of tears on Remus's face and felt another wrench of anguish. What was happening to his friends?

He curled up on a crate nearby and tried not to listen.

Sirius groaned as he came to, trying to shake some sense back into himself, and Remus's face swam into focus in front of him.

"Sirius?" he said, and the question was loaded with all the usual concern and affection.

"Moony?" Sirius was still feeling slightly dazed. "What are you doing here?"

"Here?" Remus looked around with a frown. "Where are we?"

Sirius let his head fall with a groan of despair, becoming aware of a number of thick straps binding him to the chair. "Oh, God, they got you too…" He tugged against the restraints, and found them to be completely unyielding. "Shit." How had he not noticed it was a trap? Doing his best to pull himself together, he looked up again, and a sudden feeling of sick fear dropped into his stomach. "Wait… why are you untied?"

"…I…" Remus hesitated just a moment too long, and in that moment all Sirius's fears were confirmed.

"No…" he breathed. "I was right. You're the spy."

Remus shook his head, trying to cut him off. "I wouldn't -"

But panic had taken a firm hold on Sirius now, as all the suspicions finally slotted every hint and clue into place in his mind. And that last encounter with his cousin - "Bellatrix… she tried to tell me, that crazy bitch… oh God -"

How could I have trusted you? How could I have been so stupid?

Remus was still doing a remarkably good impression of innocent concern as he watched his friend's struggles. "Sirius, you're delirious. You're not making any sense." It was the old, familiar, sensible voice, that was enough on its own to remind the Marauders that they were getting far too silly. It was the sound of a gentle guiding hand that Sirius had always relied on, had come to trust implicitly, and hearing it now was enough to crack his nerve, just a little.

"Please don't do this," he said softly. He was almost sure, now, that this was an act. "I'm not an idiot, Remus… please."

Remus looked stunned. "Sirius, it's me! Why would you even think that?"

"You're not even denying it!"

"Pads -"

Sirius leaned forward as best he could, locking eyes with Remus, both of them wearing the same desperate, wounded look. "Tell me you're not one of them," he begged, all pride forgotten in the face of the thought that Moony, his Moony, could be the traitor. "Just say it!"

"Sirius, don't…" Remus was struggling to hold back tears. "You know me."

"Untie me."

Remus hesitated, glancing around as though checking for eavesdroppers. "Let me try to find a way out of here first," he began. "I'll get us out, don't worry -"

"UNTIE ME!" Sirius snarled.

"You're being irrational," Remus said urgently, but that was too much for Sirius.

"IRRATIONAL!? LET GO OF ME!" He attempted to lunge at Remus. "YOU'RE WORKING FOR THEM!" Fuelled by seething rage and guilt and pain, all he could think of was how badly he'd been fooled. "I didn't want to believe it… God, I've been so stupid!" He jerked against his bonds viciously, struggling to get at Remus, who was just standing there calmly like everything he'd done didn't matter. "How could you do this to us?! HOW!? YOU FUCKING TRAITOR!"

A ringing silence fell, and something flickered in Remus's neutral expression at last. Slowly, the scarred young man made his way across the room, every footfall deliberate, his eyes never moving from Sirius's face. With a pang of fright, Sirius leaned back in the chair, pushing himself away from Remus as best he could.

"Calm down."

The way Remus reached out and brushed Sirius's hair away from where it had fallen in his eyes was almost affectionate, but he recoiled all the same. "Don't fucking touch me, you monster," he hissed.

"…There it is." Remus sighed and stepped back, with… regret? Disappointment? Something unreadable in his eyes. "I've always been everyone's worst nightmare. I'm just fulfilling my role. No one will ever see me as anything else. You certainly didn't."

"What are you talking about?" Sirius was expecting more hedged-around denials, more obvious lies - not this sudden turnaround - and now he suddenly felt caught out.

Remus grimaced. "Why else would you use me to get back at Snape?" he said quietly, and Sirius felt a lurch of old shame at the reminder. "I was nothing more than your plaything… your pet… your monster. You sold me out without a second thought. You exposed me to the one person that could hurt me most."

The pain in Remus's eyes was unmistakably real, and Sirius found himself lost for words. Of course, he knew he'd hurt Moony terribly with that ill-thought-out prank, but that was years ago, he'd thought it was all behind them, he'd never thought it was still cutting so deep after all this time. "I - I wasn't trying to -"

"You were always so… so selfish."

Sirius shook his head, unable to speak. Yes, I know, I was so stupid, I'm sorry…

"If my closest friend was willing to do that to me… there's not much hope that anyone else will care, is there?"

Every word was like a knife to the heart. My closest friend. Not James, not Peter. Sirius. Sirius, who'd never known exactly how he felt other than that he cared about and wanted to protect Remus, who'd trusted him, and who he'd betrayed.

"Unless I change things."

The note of iron hatred in that usually gentle voice jerked Sirius's head up, and terror closed its icy hands on his spine at the slow, cold, cruel smile appearing on Remus's face. He nearly whimpered in fear as Remus leaned close, holding his gaze with a fixed, vicious stare.

"I've never given you a reason to fear me… to hurt me… you did that on your own. Well… here's a reason."

Sirius flinched back, eyes wide with horror, as the cypress wand was levelled at his chest. This couldn't be happening, not like this, Moony wouldn't actually hurt him…

"Crucio."

Comprehension hit about a moment before the curse did, and even as Sirius jerked back in blind panic he felt a thousand white-hot knives plunge into every inch of him.

And he screamed.

The sudden shriek was enough to make even Moody jump back from the door with a string of foul language. Kingsley had gone a very odd colour indeed, and barely had enough wits about him to grab James before the young man could launch himself bodily through the doorway.

"What's happening? What's hurting him? WHAT DID YOU DO?"

"Nothing!"

"Then MAKE IT STOP!" James was almost screaming in sympathy at the sight and sound of Sirius writhing in agony. "Make it stop, whatever it is, make it stop hurting him, please -"

"I'm doing my best," Moody snarled. "I'm not enjoying this any more than you are, Potter, but shouting at me won't get the job done any faster. Sit down, shut up, and let me work." He turned back to the doorway, searching it carefully for any clues and occasionally tapping the frame with his wand.

"…Nightmare Curse," he grunted eventually. "Nasty one, too."

"What's it doing?"

"It's on the same principle as a Boggart," Kingsley explained. "Gets into your head, finds your fears, and traps you in a nightmare so you can live them out." He grimaced. "Very effective capture and torture method in one."

James groaned miserably. He knew the kind of things that went on inside his friends' heads. If that wasn't enough to torture the pair of them he didn't know what was.

"Can you break it?" he managed after a moment of struggling to shut out the screams. "Please."

"It'll take a bit, and we'll need to concentrate, but yes."

James nodded and returned to where he'd been sitting, curling up and fighting the urge to cover his ears. Listening to his friends' torment, while he couldn't make it stop, was almost too much to bear.

"You thought wrong."

Remus flinched and closed his eyes. "Stop it," he begged, but Sirius's voice continued to bore into him, loaded with venom.

"You thought I had feelings for you."

"Pads, please -"

"The idea of being with you makes me want to puke, Moons." The disgust and loathing was unmistakable as Sirius pulled away. Remus felt his stomach coil with shame.

"If you're going to kill me," he choked, "for the love of Merlin, get on with it."

"What, you don't want to know who's next first?"

Remus's head jerked up, eyes wide with shock. "W-what do you mean next?"

"You think you're the only one I'm getting rid of?" Sirius sneered. "Nah, you're just the first. The Order's falling apart. And Lily and James are next."

Remus felt the blood drain from his face. "No… you - you can't - their baby -"

"The Dark Lord wants them gone, Moony, and guess what? The only person who might have figured it out handed himself to me on a silver platter!" Sirius was nearly laughing again. "All because of some sick idea that I might have cared about him."

Remus shook his head, nearly speechless at the horrific knowledge of what was coming. "P-Pete might figure it out…"

Sirius really did burst out laughing at that. "Oh, please! Peter needs a diagram to figure out his shoelaces!" He jabbed a finger into Remus's chest. "You were the only one smart enough and suspicious enough to have got me caught, and you happily blinded yourself. So when you see them in whatever afterlife you end up in, you can have a nice long chat about why you let them die."

"No…" Remus was crying helplessly again, twisting against the straps as he begged. "Pads, you can't, he's your best friend, he trusts you -"

Sirius leaned in, settling his hands on the arms of the chair, and the slow, twisted smile spread across his face again. "But Moony," he said sweetly, "that's what makes it fun."

Surely it couldn't take much longer, James thought as he watched Kingsley and Moody trying to break the curse. He didn't know what was worse, the screaming or the broken sobbing caused by whatever was crawling through his friends' minds.

He pushed himself up angrily and made his way back to the cellar door, where Peter and Frank were still on watch. Well… Frank was. Peter was curled up on the floor with his head in his hands, evidently trying to block out the noises echoing down the room.

"What's going on?" Frank said quietly. "We heard the screaming and shouting, but that doesn't explain anything and it just about broke Peter."

James swallowed hard and crouched to give Peter a one-armed hug. At least there was one friend he could still do something for. "They, uh… they walked into a cursed room," he said. "It's put them to sleep, and now they're stuck in a nightmare. I don't know what's happening other than that."

"But it can be broken, right?"

"They think so." James jerked his head towards where the senior Aurors were working. "Just a matter of time, though I don't think they're gonna be in very good shape once they're out."

"They'll be okay in the end, though," Peter said shakily, and then glanced up at James. "…They will, won't they, Prongs?"

James managed a smile. "'Course they will. They're tough. We'll just have to look after them till then."

Peter gulped, nodded and curled back up. With a heavy sigh, James sat down beside him, wishing it was all over.

It seemed to go on forever, but the pain finally came to an end, and Sirius slumped in the chair, gasping for breath. His throat was raw, and every inch of him, inside and out, felt like it had been beaten.

The sound of footsteps and the scrape of a chair reminded him where he was and what was happening, and the rage it ignited gave him the strength to raise his head and look Remus in the eye again, even though every muscle in his body was shaking with the strain.

"Monster," he snarled.

Remus shrugged. "You know, all those years you and the others spent telling me my problem didn't matter… I almost began to believe you. I began to think maybe, if I played the good little member of society, there was a chance I could really find… someone." He laughed bitterly, and for a fleeting moment Sirius saw the familiar sad, wistful, longing look he'd never known how to respond to. "But then you made it very clear what you thought of me," he went on, the cold expression returning. "So I figured, well, if I'm a monster… I may as well do what monsters do."

"And that means this?" Sirius yanked at the straps, trying to shut out the little voice whispering your fault, all your fault at the back of his mind. "Kidnapping and torturing me?"

"You've got to pay," Remus snarled, and the wolf rose behind his eyes at last. It was the vicious animal intelligence Sirius had seen every full moon since he'd become Padfoot, but seeing it here on Remus's human form was far more terrifying, and he shrank back, swallowing hard.

"Pay for what?" he managed eventually, his voice shaking more than his hands.

Remus leaned in close, utter loathing and hatred in every line of his face. "For ten years of lies, Pads. For ten years of pretending you ever really cared about me, when all this time you would have turned on me in a second given half a reason. I'm done trying to be good."

Sirius couldn't speak. Fear and guilt had combined to render him utterly speechless. His willpower failed at last, and two fat tears rolled down his cheeks.

"Nothing to say?" Remus said, with a mocking little chuckle. "That's a first. Maybe I'll loosen your lips the old-fashioned way."

He raised his wand, and Sirius flinched, closing his eyes as he braced for the next dose of pain.

A flash of white light illuminated the cellar, and a crash echoed from end to end.

James was sprinting down to the hidden room before the echoes had begun to fade away, with Peter close behind. "What happened? Are they okay? Are you okay?"

"Curse's broken," Moody replied, waving the dust away and eyeing the door, which had been blown off its hinges. "It'll take them a few minutes to come round, I reckon. Might be best you two got them back to Headquarters, give them somewhere safe to wake up."

"Sure. It's safe to -"

"Yes, get in there."

James ducked into the room immediately and crouched next to his friends, relief and guilt mingling as he took in how broken they both looked. "It's okay," he murmured, giving them both a reassuring squeeze on the arm. "It's all going to be okay. We've got you."

Peter joined them, pale and scared, but he took Remus's arm in a firm grip and the four of them vanished from the manor.

The light seemed almost blinding as Remus opened his eyes, bewildered. One moment Sirius had been smirking at him, and then he'd just disappeared and -

James's face swam into view, creased with worry. "Moony? You okay?"

"Prongs," Remus gasped, and the worry faded into relief.

"You're okay, thank Merlin. What the hell happened?"

"Where is he? Where's Sirius?" Remus tried to sit up, but James stopped him firmly.

"It's fine, he's fine, you're both fine -"

"No, you don't understand, he's the spy, he -"

" - let me up, Pete, we need to stop him, he's the spy!"

"You fucking dare -" Remus snarled, nearly rolling off the bed as he tried to get out of James's grip, and found himself face to face with Sirius on the other bed just a few feet away. Both of them wore the exact same expression of barely-repressed panic, rage, and betrayal, which shifted to utter confusion as they stared at each other.

"Both of you, stop now." The absolute certainty in James's voice silenced them both. "Neither of you is the spy, okay? It wasn't real."

"…How do you know?" Sirius was still gripping Peter's arm as though ready to shove it away.

"It was a curse. You walked into that hidden room at the manor, right? There was a curse set over it. It put you both into a nightmare and we needed to break you out of it to get you out safe."

"But I -" Sirius stared at James, then Remus, then shuddered and looked away. "It was so real. The Cruciatus and… everything."

"Cruciatus?" Remus's voice shook as he sat up slowly. "You were Cruciated?"

"Yeah." Sirius dug his fingers into the blankets. "By you."

A wounded noise escaped Remus, and he sank back onto the bed. "No. I - I wouldn't. Not ever."

"Maybe you two should straighten this out between you," Peter suggested tentatively. "Now you both know what's going on."

"Sometimes you come up with the best ideas," James said, trying to put on a bright face. "All right, you two, you heard the man - talk this out. Everything from walking through that door to waking up here - it wasn't real. And no fighting, or we're coming back to separate you." With that, he led Peter out of the room and shut the door firmly.

There was silence for a while as the pair gathered their wits and tried to reassert the reality of the situation on their senses. Finally Sirius broke the silence. "I called you a monster," he admitted, cringing at the memory. "After I was convinced you were the spy. And you - I've never seen you so… cold."

"You told me I was a creature that you didn't need a reason to put down." Remus's voice cracked. "You laughed at me when I asked you why you were doing it. I couldn't -" He hid his face in his hands. "I was nothing. Just something to be taunted and laughed at."

Sirius felt his eyes burning, and swallowed the lump in his throat. "You said I didn't see you as anything more than a pet monster. That it was that stupid, stupid thing that happened with Snape that proved I didn't care. You said you'd never given me a reason to be scared of you… and then you - did the - the spell."

"I couldn't hurt you like that," Remus whispered, and felt tears spill down his cheeks again.

"You're not a monster," Sirius replied, and his voice broke. "Moony, I'm so sorry, so sorry for every stupid thing I've done to you."

"I know. It's okay, Pads. I promise."

A few moments of silence later, after some nudging from his conscience, Sirius cleared his throat and said, "You, uh… said something about hoping you could find… someone. And you… looked at me…" He saw the scarlet creep up Remus's cheeks, and winced.

"You told me you knew how I felt about you." Remus was staring resolutely at his white-knuckled hands. "And you said… you said the idea made you want to puke."

"Idea of what?"

"…Being with me."

Sirius glanced up, and saw all the familiar signs of panic, nerves and fear of rejection in Remus's rigid posture. He swallowed hard and shook his head. "Then I guess that twisted bastard version of me had no idea what he'd be missing out on."

"…You mean that?" There was an almost desperate note of hope in Remus's voice as he looked up, and Sirius saw the spark of shock and delight that always lit up his friend's face at the idea that someone might want him around.

It wasn't hard to give him a little smile. "Yeah, I mean it. But listen - Moony, let's just… get some rest, okay? We've had a bloody horrible night, we're both wiped, and I need to get my head back together."

"Good point." Remus managed to smile back. "I just… Pads, whatever I did to you in there…"

"You didn't do anything," Sirius cut him off firmly. "It was some freaky dream-thing that looked like you. That's all. Okay?"

"…Okay."

"Good." Sirius smiled briefly. "Now shut up and go to sleep. I will if you will."

Remus lay back down and drew the blankets over himself. He was almost positive he'd never get to sleep, not with the thoughts and memories running through his head.

Less than five minutes later, Sirius heard him snoring, and couldn't help but smile.