After a while, Zuko gave up calling for help. Some time after that, he quit pacing and thought. He couldn't get out the way he came in. That didn't mean there was no other way out. Zuko held his hand out and called up a flame, and sighed with relief when fire licked his fingertips. The darkness wasn't dispelled far, but he could now see a few feet ahead of him, and he realized that he was standing on a dark marble floor. He followed it cautiously, wary of what might be waiting outside his bubble of light. After a while of walking, his fire glinted off of something. He paused and stared the circular hole. His fire was reflecting back at him. Hesitating just a moment, he put it out and found himself looking out into a darkened room. A room he recognized. He was in one of the empty bedrooms in the summer palace. His father's if he recalled correctly. Zuko surged forward, pressing on the glass, but it didn't budge. He was in the summer palace, or at least in the mirrors. That was something. Zuko picked up running along the corridor again, stopping an looking out of different mirrors in the hallways, the bathrooms, the foyer. Finally, he came upon an occupied room.
Katara sat in the library, relishing in a rare moment alone. She'd found an old romance novel and was idly skimming it when the door opened. Zuko watched in horror as he walked in. What would this doppelganger do to her? He beat his fist on the glass and screamed Katara's name. He needed to get out of this prison! How could he make himself heard?
"Katara!" Zuko screamed. She frowned, and started to turn. She had heard him! Zuko doubled his efforts, screaming and banging his fists on the glass until he was certain it would break. But the other Zuko slipped between Katara and the mirror, and smooth as a serpent, sat down beside her. He sat down right beside her. Katara's attention was drawn away from looking for the source of the sound and was now nervously focused on the boy beside her.
The mirror creature was murmuring something to her. Zuko pressed himself against the glass, trying to hear what was going on, but the sounds were muffled and both Katara and the creature were speaking too low. Zuko watched in growing horror as the Mirror Zuko leaned closer to Katara and began playing idly with the end of her hair. Katara's face had gone red, and her eyes were wide with surprise, but she made no attempts to move away. Not even a few moments later when he got even closer, until their noses were almost touching. Katara's eyes fluttered, her lids lowering until they were almost shut. Zuko stopped breathing as the mirror creature leaned in to close the last little bit of space...
Katara's eyes flew wide open and she gasped. A moment later, the door of the library burst open, and suddenly Katara was on her feet with the sofa between her and the boy still leaning forward for a kiss. Sokka rushed in, shouting excitedly about his success in mastering a sword fighting technique. He wanted to show them in the courtyard, and asked Zuko to spar with him to show it off. Katara nearly ran after her brother, casting one last pondering glance at Zuko. The mirror creature waited until they were gone before his pleasant smile twisted into a dark scowl.
Zuko banged on the glass of his prison again, shouting for the creature's attention. At first, Zuko thought it couldn't hear him, but then it smirked, turning it's head slightly in Zuko's direction, but not looking directly at him.
"I can see why you like her," it said, it's voice muffled as if it were speaking through a closed window. "I think I will, too."
"You stay away from her!" Zuko shouted, pummeling the glass again. "You stay away from all of them!" The creature just chuckled and left the room, shutting the door behind him.
Zuko ran down the dark corridor, frantically looking through mirrors for a glimpse of his friends. They must have been outside, because he couldn't find them in any of the rooms. His throat was growing sore from screaming for anyone who could hear him, and his body was sore from sprinting the hall and beating on the glass. He slumped against a wall, allowing exhaustion to catch up with him. Despair, he thought, would come any minute, but to his distant surprise, it hadn't. After all, this was par for the course for him. Perhaps he never considered his fate might be exactly this- trapped in some horrible mirror world while he watched his doppelganger take his place among his new friends, and make moves on the girl he...- it was still not surprising to him that just when he thought his life had taken a turn for the better, something terrible would happen. At least he wouldn't have to wait long for death, he reasoned. He was already hungry and thirsty. He figured dehydration would kill him a few days. He just hoped he would have a chance to warn his friends about the imposter before he went.
Adrenaline surged through Zuko's body like a bolt of his sister's lightning. Every hair on his body was standing on end, and he instinctively fell into a defensive crouch, facing the direction the voice had come from. At first, he saw nothing, but he expansive darkness, but then he noticed a figure- tall and pale- approaching him from the pitch dark. He was glowing, Zuko realized with a start. The man had long white hair and a carefully sculpted beard. His hair had been pulled into a top knot with a small flame securing it. Through the shrouding of ethereal light, Zuko recognized that he wore the formal robes of Fire Nation nobility.
"It is so good to meet you, my grandson," the man said smiling. "I am Avatar Roku." Zuko gasped and stumbled backwards. He saw the resemblance now. Roku had the same nose as his granddaughter Ursa. The same mouth. The same slant to his eyes. The features Zuko had inherited. He could only gape at the older man- no, the spirit.
"A-am I dead?" he asked. Roku chuckled and shook his head.
"Thankfully, no," he said. "And you won't die here. It'll be uncomfortable for you, but you're essentially immortal here, although you'll still feel hunger and thirst and such. But none of that matters, because we are going to get you out of here."
"What is this place?" Zuko asked.
"You're in..." Roku paused and looked around thoughtfully. "Let's call it an annex of the spirit world. You see mirrors can serve as a sort of gateway, if you know how to use them. "
"How do I get out?" Zuko "I'm not even sure how I got in!"
"You got caught by a lesser spirit," Roku explained. "Some of them are nasty buggers, but mostly harmless. Unfortunately, your grandfather, Azulon was attempting to recruit spirits to fight for him, and foolishly didn't see to it that all the portals he tried to open were sealed."
"Of course," Zuko groaned, rolling his eyes. "It's not enough that I pay for my own sins, I still have to deal with my family's, too?"
"That is, unfortunately, what comes with the territory," Roku sighed sadly. "You will one day be the Fire Lord, and it will be your duty to make amends for the sins of your forebearers. But compared to untangling the mess of the spirit world, that'll be a cake-walk. Especially, if you keep the right people by your sides." Zuko stared at Roku, mystified.
"Are you sure you're related to me on my mother's side?" he asked. "Because you sound just like my uncle." Roku chuckled and shook his head.
"I know of your uncle Iroh, and I respect him a great deal," he said. "I'd be happy to claim him as a grandson, but no. The only connection I have to that side of your family was my friendship with your great-great-grandfather. Now, to get you out of here."
Zuko was waiting once night fell and everyone began to turn in for the night. Roku had gone some time ago, wishing his grandson luck, and Zuko was alone. Finally, the door to the bedroom swung open and Katara entered. He waited until she had shut the door and lit her lamp to begin banging on the mirror and shouting her name. This time, Katara heard him immediately. She looked over at the mirror in confusion and gasped.
"Zuko?" Her mouth hung open in shock.
"Please! Don't freak out," Zuko begged her. Katara stood rooted to the spot, gaping at him. She looked over her shoulder, towards where she had just said good night to her friends, Zuko among them. Then back towards her mirror in confusion.
"What?" she whispered, taking a cautious step forward. Zuko slumped against the glass in relief.
"It's me Katara," Zuko told her.
"Zuko?" She got closer, inspecting the mirror. She looked behind it to see if there was a door or something she hadn't noticed before, but the mirror was attached to the dressing table, leaving a gap of several inches between the back of the mirror and the wall. She moved in front of the mirror and frowned when she saw her reflection in front of Zuko. "How are you doing this?"
"I'm trapped!" Zuko told her. "That-that thing out there, it isn't me. I was in the woods, and there was this huge mirror, and when I looked into it, that thing grabbed me and trapped me in here. You have to believe me! That isn't me out there!" Katara stared at him for a long moment before shutting her eyes and taking a deep, shaky breath.
"I believe you," she said. Zuko hadn't been expecting that. He had planned a whole list of proof of what he was saying, but it all flew out of his head.
"I knew something was off when he came back," Katara explained. "He was acting weird, and he didn't know where the dining room was. And then later he almost...I saw him close up and I realized his scar was on the wrong side."
"What?" Zuko gasped. He hadn't noticed. He hadn't even paid attention to that.
"I thought I was crazy," Katara said. "No one else said anything, so I thought maybe I was wrong, but..." Her eyes swept over his face and she nodded slightly. "I was right."
"Thank Agni," Zuko sighed. He leaned forward, resting his forehead against the glass. His throat closed around a sob and he thought for a moment he would weep with relief.
"How do we get you out?" Katara asked, pulling Zuko's focus back.
"He needs to look in a mirror," Zuko explained quickly. "He's part of this world- the spirit world- so any mirror will do to bring him back in." Zuko was glad when Roku told him that although the spirit needed Zuko to look in that specific mirror in the woods, he didn't need the spirit to go back there. He didn't think he could guide any of his friends to the right spot, let alone trick a spirit who had no inclination to go back there.
"I don't know how to get him to look, though," Zuko said. "He purposely avoided looking in the one in the library.
"Y-you were in the library?" Katara's face went suddenly red, and then Zuko's face flushed, too.
"I-I was just looking for a way out," he said. "I wasn't spying." Katara dropped her gaze and shifted on her feet.
"It's..." she huffed and shook her head. "Whatever. It doesn't matter. I have an idea. Just wait here for me. Don't move, okay?"
"Alright," Zuko said. Then Katara grabbed one of the tarps that had been covering the furniture when they arrived, and threw it over the dressing table. Zuko was plunged into darkness. His pulse quickened, but he swallowed hard and forced himself not to panic. He could trust Katara.
A few minutes later, he heard the door open again. There were low voices and some giggling that sounded like Katara.
"We have to be quiet," Katara was saying. "If my brother catches you in here, he'll kill you."
"Oh?" Zuko heard his doppelganger chuckle. "Don't worry, love, I can keep a secret." They stopped talking for a long, uncomfortable stretch. Zuko tried to peer through the tarp, but it was too thick. He heard footsteps stumbling across the room.
"No," Katara said sharply. "Not the bed. We're not quite there yet."
"Whatever the lady wishes," the mirror creature purred. There was another stretch of quiet. The footsteps stumbled closer and Zuko heard them bump against the dressing table. Then suddenly the tarp fell away and Zuko saw himself and Katara locked in a passionate embrace for a split second before the mirror creature glanced up and found himself staring into Zuko's scowling face. He only had moments to act. Zuko felt the moment he connected with the spirit, and he reached through the mirror- now as liquid as when he was pulled through- and grabbed the creature's throat with both hands. Then the yanked him forward and pulled him through.
On this side of the mirror, the creature no longer looked like him. It was a small, shadowy figure cowering before Zuko. Remembering Roku's instructions, Zuko didn't hesitate. He called up a ball of fire a hot as he could manage and incinerated the creature. It wasn't dead, Roku had warned him, but it would be a long while before it would be able to pull itself together. That done, Zuko launched himself at the glass, landing in a heap at Katara's feet. She reached down and hauled him to his feet, studying his face carefully.
"It's you, right?" she said.
"It's me," Zuko assured her. Katara still looked dubious.
"What did I offer you in the caverns beneath Ba Sing Se?" she asked. Zuko winced, remembering that day.
"To heal my scar with the spirit water," he replied. Katara melted in relief.
"I mentioned that day to the mirror thing," she said. "And he had no idea what I was talking about. He thought we'd had some kind of tryst. I figured it was as good a reason as any to get him into my room."
"Smart," Zuko mumbled. He looked down at his feet, trying to let go of the sudden pang of anger in his stomach.
"I'm glad you're okay," Katara said, hugging Zuko. He relaxed into her embrace. But gradually, as the fear from his ordeal receded, a new realization dawned on him. Katara hadn't known the mirror creature had taken his place in the library, and she hadn't been opposed to a kiss from him. That thought chased away what lingered of his jealousy, and hope sprang up in it's place. Maybe, he chuckled to himself, the mirror creature had done him a favor after all.
The next day, he would take his friends and destroy his grandfather's spirit portal. Then he would find the pond he'd been looking for and take Katara there. It would be the perfect spot to confess his feelings.