A/N: So, I wrote this just a little bit after Thor 2 and never got around to editing and posting. Oops.

Disclaimer: I don't really own any Thor stuff, just messing with possibilities a little.

Loki proved to be a nuisance, even after he was caught and shackled. Thor had led him into Asgard, brought him before the All-Father for sentencing, and then helped escort him to his jail cell. And after that was all said and done, Thor found himself besieged for information by friends and family, and asked to make a formal account of Loki's capture to his father.

Thor was kept so busy that he didn't notice Sif's absence until a week later, when he thought to go hunting with her and the Warriors Three to clear his mind.

He looked everywhere for her with greater and greater alarm. She had no hiding places that he knew of, nowhere she would go to escape. She was always eager to be by his side, blunt to a fault and openly desiring battle. She was not one to ever be secretive. Secrecy was Loki's game. And the dungeons were the only place Thor had not yet checked.

"Has Lady Sif been down here?" Thor demanded.

It was no secret that Sif despised Loki and the feeling seemed to be mutual. There was nothing Loki could do to her from inside his cell, but as unlikely as it sounded, Thor held hope that perhaps she had come to mock him and Loki had said something to make her storm off and sulk.

Loki studied his fingernails. "Yes and no." But he was smiling that small, secretive smile that meant he knew something Thor did and was rather proud of that fact.

"That is not an answer," Thor growled.

Loki looked up, his eyes going wide with mock surprise. "She has disappeared."

Thor sighed. "Yes, brother. That is why I am looking for her."

"You misunderstand me." Loki leaned forward, his smile stretching. "She is gone. Probably for good. You'll never find her."

"Where? Where has she gone?"

Loki shrugged and leaned back against the wall. "The same place everything goes when it disappears. Maybe nowhere or maybe everywhere at once." He swirled a hand through the air and his eyes became distant.

Thor hated to let Loki go when he so obviously knew something. Something important. But demanding answers when Loki was in this sort of mood would get him nowhere. The more he pushed, the more evasive Loki would get. But Loki's words had unnerved him and he would not rest until he knew Lady Sif was not in some sort of danger. So he went next to Heimdall.

Heimdall did not look at him as he approached, his far-seeing gaze fixed on something in the distance. But he nodded, acknowledging Thor's approach. "Greetings, Prince Thor. A fine day for a hunt, is it not?"

Thor wasted no time on such pleasantries. "Where is Lady Sif? I know you can see her."

Heimdall was silent for a long moment. "There is no Lady Sif," he said at last.

Thor bowed his head. "She is dead, then?"

"There was never a Lady Sif."

"Impossible," Thor said indignantly. "I have fought side by side with-"

"An illusion. And a very good one."

Thor opened his mouth to ask who would be able to do such a thing. But he realized he already knew.

Loki.

It didn't make sense. He sifted through memories of Loki and Sif fighting side by side, of them sparring together, of Sif aiding in the fight against Loki. It didn't make sense for Loki's own creation to fight against him. But Thor knew it to be true, knew it with more surety than he had known anything else.

Loki had not only created an illusion with physical form and a full personality, but he had maintained that illusion for centuries, making careful changes to Sif's form as she was supposed to age and mature alongside them. Thor had scoffed at Loki's magic before, thinking him only capable of conjuring up mist to shield them in battle or copies of himself to make mischief. But this was a deep magic. It had to have taken considerable effort for Loki to manage. To what purpose? Thor couldn't even begin to guess. Loki was the only one who would know.

Thor reminded himself that Loki was in a mischievous mood. All he would hear from him would be lies and half-truths, if he answered him all. But Thor's feet still carried him back to the dungeon.

Loki greeted him with a mocking smile. "Sif's not here, Thor. I can't believe you still think I've done something to her. You know my magic is bound behind the barrier."

"And that is why Sif has disappeared," Thor said. "Because of that barrier."

Loki's smile faltered. "How did you find out?"

"Heimdall told me."

"Oh, of course." Loki rolled his eyes. "How silly of me to overestimate your intelligence."

Thor sank down onto the floor in front of Loki's cell. "And all these years I have underestimated yours."

Loki was silent for a moment and then grudgingly, he added, "I suppose I can't be too upset with my own success. "

"And what a success it was, brother," Thor said, seizing the opportunity to appeal to Loki's ego. "You have managed to deceive just about everyone in Asgard. This has definitely been your greatest scheme yet."

Loki frowned. "I am not sure whether to take that as a compliment or an insult."

"Brother, do not look for hidden meanings in my words. I am genuinely impressed by your magic skill. Sif first appeared when we were only children."

Loki shrugged. "It was not that difficult," he said. "Illusions have always come easy to me. And the secret to giving them solid form was in the first spell book I ever read. Hardly anything impressive."

Thor was irritated by Loki's dismissive attitude. He had offered Loki the praise he so desperately craved, and his brother had thrown it back as if worthless. Thor reminded himself that Loki was only acting this way because he was trapped in prison. Loki was frustrated at being imprisoned, at having his favorite illusion taken from him, so he was acting out in the only way he knew how. So as much as Loki would scorn him, Thor knew that he couldn't stop complimenting Loki's cleverness, because eventually, Loki's hurt would subside and he would be pleased and flattered by praise and be willing to tell him all about the secret plan that Thor had fallen for all these years.

"It was more than physical form," Thor said. "It was Sif's behaviors, Sif's personality. How were you ever able to concentrate on Sif's actions at the same time as your own?"

"That was also fairly easy," Loki said, although Thor didn't miss the slight hint of pride in his eyes. "When we were younger, I had to think about each of her reactions, but after a few years, her personality became set. As long as I funneled magic into her, she went on acting like a living woman. A brave warrior."

Loki's mouth twisted into a sneer. "Dear, honorable Sif, with her blunt speech and lust for war. Nothing like Loki. Loki is a coward who hides behind his magic because he's too weak to fight. Loki the liar, Loki the monster, Loki the-"

"Brother, stop!" Thor demanded, smashing a fist into the barrier.

Loki subsided. The madness in his eyes faded and he smoothed down his tunic, affecting an air that the outburst hadn't just happened.

Thor swallowed. The words were familiar. He had heard them before, but from Sif's mouth. Sif was always angry with Loki and Thor had always tried to placate her rage, assure her that she was still beautiful even with green hair, that Loki was just bored, that he meant no lasting harm, that killing Loki would be unnecessary. He had thought he had been saying all the right things because Sif and Loki had never come to blows. But maybe all these years, he had been saying all the wrong things.

"Loki," Thor began again. "Why did you make Sif hate you so? Why does she always say such hurtful things about you when you could have chosen to have her think favorably of your magic?"

"Let's think that through," Loki said. "If Sif thought only the world of me, you wouldn't believe for a second that she was real."

"I suppose not," Thor admitted.

Loki shifted, bringing his chin down against his knees. "I will say that I never planned for this to go quite this far," he said.

And Thor knew that was as close as Loki would ever get to expressing regret.

"Brother," he said gently. "There is still time to change-"

"Change?" Loki demanded, rising to his feet. "Look at me, Thor. I am in prison. You can't change this."

"I can change the way people see you. If they knew all this time that Sif-"

"No," Loki said. "Don't you dare take that away from me." He scowled and crossed his arms over his chest.

"Brother, I am trying to help."

Thor sighed. Loki was hard to understand. It was almost as if he wanted Thor to have immediately seen through the Sif charade and at the same time wished that he would have never found out.

"You can't help me," Loki said. "You can't even help yourself."

"I can help you, brother. If you'll only tell me what you want from me."

Loki's eyes narrowed. "What I want? No, it doesn't matter what I want. You've never cared about what I want and now is not the time to start pretending."

"Brother, I have always cared about you. If I didn't care, I would have killed you instead of bringing you back home."

"I wish you had," Loki said darkly. "You've brought me back just to be exhibited like a zoo animal for your precious friends. I'm sure you've all had a good laugh now. 'Look at Loki, the poor caged beast. If only Sif were here to see this.'"

"Brother," Thor said. "I know you are upset about Sif's loss. I can't fathom why you needed to make an illusion to keep you company when you had so many other friends-"

"They were never my friends!" Loki practically shouted. "They turned on me the instant Sif showed up. And you too, Thor," Loki spat. "It's so like you to be swayed by a woman's wiles. You couldn't even control yourself around her, you great oaf."

"Brother, what are you talking about?"

Thor had always had affectionate feelings for Sif, but he had never acted on them. He thought that had taken a great deal of control, but if Loki knew how he felt about Sif, obviously he hadn't been as discrete as he had thought. Somewhere along the line, he must have made some embarrassingly lovestruck expression.

Loki's eyes gleamed. "You may not remember what you do in your drunken excesses, but I do. I've seen it all so clearly." Loki stretched his hand out, tracing it along the barrier. "I've seen every time you've bedded the lovely Sif, whispered slurred words of affection, told her secrets you could never tell me." Loki sank back down to the floor. "Yes, Thor, if only you knew your lover would only be as loyal to you as I was."

"Lies," Thor said vehemently. "Sif was never-"

"Never your lover? What a pity." Loki reclined on the floor, propping his head on one hand "After all those drunken romps, I would have thought you'd at least feel something for her. But maybe, maybe she was only a warm body, just an outlet for your release."

"You lie," Thor said, feeling his blood boil with rage. "Lady Sif has always been my friend and nothing more."

"You needn't keep up the pretenses, Thor. It's not like Father will ever hear about this. He has much better things to do than keep an eye on me." Loki rolled his eyes. "So don't try and pretend you never had any feelings for her. I know you too well. I know how you get when you drink. The way you feel like you can do anything, take anything, no matter what the consequences."

"Loki," Thor said warningly.

But Loki refused to be silent. "I wouldn't say it was rape," Loki said slyly. "Sif always did have feelings for you. But I think you might have been a little rough with her. But what does it matter? She wasn't a real woman."

"Shut your mouth, Loki," Thor growled. "I don't want to hear another malicious word from you or I'll silence that lying mouth for good." His hands curled into fists at his sides.

"Go ahead," Loki said. "I dare you." He was standing again, his arms spread wide. "Why don't you try and make dear Sif proud by giving me the revenge she's always wanted? You know how often she spoke of my bruised and bloody body-"

"No," Thor said. "I won't give you the satisfaction." He turned and walked resolutely back out of the prison, feeling victorious as Loki slid back to the floor of his cell.

Thor did not return to Loki's cell for almost a year.

He had had every intention of never going back to see him. Loki deserved to live out the rest of his days alone after what he had said to him. Accusing him of rape just for sport. Thor didn't see how anyone could sink down further.

But the situation had grown dire. He needed to get Jane out of Asgard, and bring the fight to the Dark Elves so they could destroy the Aether once and for all.

As distasteful as it was, Loki was their only hope now.

"After all this time, now you've finally come to visit me," Loki sneered.

Thor was unimpressed with the illusion Loki had conjured up to meet him. It was all bared teeth and proud warrior spirit. "No illusions," he said, irritated that Loki had put so little effort into his illusion even more so at the fact that he had put up an illusion to begin with.

The real Loki gazed at Thor impassively from the back of the cell. He was sprawled out on the floor, looking bored, tired, listless. His hair had grown longer and Loki had made no effort to smooth it out. He was the very picture of a broken man, but Thor could not trust appearances. As Loki was quick to remind him, that would make him a fool. And Thor was very tired of being Loki's fool.

Thor told Loki the plan, knowing there was nothing he could do to make Loki help. And knowing all the warnings in the world wouldn't be enough to stop Loki from betraying him if he really wanted to.

Loki favored him with a tired smile and asked, "When do we start?"

That was all the assurance Thor would get that Loki would cooperate and Thor accepted that.

Loki's listlessness was gone as soon as they'd begun their escape. Another trick, Thor thought glumly. Loki seemed downright giddy as they raced along through the palace to meet up with the Warriors Three. Maybe it was the exhilaration of freedom, or more likely, delight in knowing just how many rules they were breaking at that very moment, of knowing how much trouble they would be in if they were caught.

Loki didn't listen when Thor told him to be unobtrusive, shapeshifting into various forms before settling on Captain America. And then Thor pinned Loki into a pillar and warned him never to take on his friend's shape again. "This is serious," Thor growled. "This is no time to play around."

"I know," Loki said quietly, gesturing with a tilt of his head.

Thor turned to look.

Sif was standing with her arms crossed over her chest, the faintest smirk on her face.

"What is she doing here?" Thor hissed. "I asked for your cooperation, not for your continual mockery."

"As you said, this is a very serious matter. We'll need all the help we can get, right?"

Thor released his grip on Loki's shoulders. He hated to admit that Loki was right, especially when he looked so smug about it. But he was right. Running along the corridors with Sif and the Warriors Three felt right. They had fought together, all together, so well in the past. It was unthinkable to fight without Sif at his side.

But at looked like there wouldn't be another chance. Thor could hear the guards coming down the halls, loud shouts and footsteps.

"I'll hold them off here," Sif said. She dropped into a fighting crouch.

Thor glanced at Loki who only smiled. "I told you we would need her one last time," he said.

"Will you be able to maintain this illusion after we are gone?"

Loki rolled his eyes. "She only needs to aid our escape. She has no purpose after that. Now, stop worrying. I have everything under control."

"Go on ahead with the others," Sif said, jerking her head towards the Warriors Three hurrying down the halls up ahead.

Thor nodded, feeling a little foolish for still doubting Loki's abilities. He nodded a last farewell to Sif and moved to join his friends.

Out of the corner of his eye, he saw Sif draw Loki aside and he was still close enough to hear her words to him.

"If you betray him, I will kill you," she said threateningly.

Thor immediately turned and marched back to confront Loki. "Don't say such things," he said, looking fiercely at Loki.

Sif stepped in front of Loki. "Why shouldn't I?" She raised her chin, still looking every bit the brave, haughty warrior woman Thor had thought he loved. "He is a liar, a murderer, a traitor-"

Thor shoved her aside and stood in front of Loki. "Brother, I don't understand. Why do you have her say these things about you? Why must you torment yourself so?"

"You don't see?" Loki sneered. "You are an idiot, as always. You've had enough time to accept the traitor in your midst. The monster living among men. Harden your heart and accept the reality."

Loki stiffened as if bracing himself for a blow and Thor suddenly understood with awful clarity: No one would ever hate Loki the way he hated himself.