The sun was just starting to dip below the horizon as they walked back to their guest house. Katara was tired, but extremely satisfied with her training. Master Pakku had told her that she progressed faster than any other student he taught, and was now nearing mastery of her element.

Princess Yue was improving as well. Chief Arnook had, albeit reluctantly, allowed women to learn combat waterbending if they wished to. Sokka and Yue had been the ones to ultimately convince him; Sokka had told him of the raids their own tribe had endured over the last hundred years, reducing them to a handful of warriors and one waterbender. Yue had eagerly volunteered to learn, and Master Pakku had quickly gotten over his initial hesitation to teach her after she pulled out her glittering knife and chopped off the end of his goatee.

Aang walked beside them, tip-toeing on the edge of the canal with his arms out for balance. Master Pakku was less than pleased with his progression, but Aang didn't respond as well to Pakku's rigid and blunt coaching. He needed a gentler approach, with lots of encouragement and praise.

She pulled back the furs to their guest house and found Sokka, who sat with his feet up on the table and a look of extreme concentration on his face. He was carving something for Yue again, determined to create something they could actually recognize (he was still insisting that his fish carving didn't look like a bear).

Zuko and Azula were huddled together beside the fire. Katara shrugged off her parka before squeezing herself next to them. Zuko shuffled over to make more room under his blanket.

"How was practice?" He asked as she snuggled closer to him. She wasn't cold, but they just looked so comfortable that she couldn't resist.

"It was great! Yue mastered the squid forms today."

The princess smiled, settling next to Azula. "And Katara has nearly mastered waterbending."

"Really?" Zuko nudged her, and she found herself blushing as he smiled. "That's even faster than Azula."

His sister huffed. "Our training was cut short, Zuzu. And I could defeat any of these waterbenders easily."

Yue giggled. "You think you can beat a waterbender while in a city made of ice?"

"Of course not, that would be idiotic." Azula waved her hand dismissively. "Obviously I meant in a duel on equal footing."

"You would have to come out of your blankets first," Sokka pointed out. "And you haven't fought in a while, you're probably a bit rusty."

"Well it's not like we can practice here," Azula fired back. "If any of them realize who we are then we'll be killed on the spot."

Their cheery mood dampened. Katara did her best not to think about it, and they haven't really discussed it as a group. The Northern Water Tribe was well known for their hostility and ruthless patrolling of their borders- what would they do if they found the former prince and princess of the Fire Nation in their city? Yue's silence did nothing to soothe her fears.

Sokka broke the silence. "Yue, do you want to feed Appa with me?"

"Oh!" Yue scrambled to her feet. "Yes, I can't believe I haven't met him yet!"

"Appa's the best, you'll love him!" Aang said. "I'll come with you guys."

"Uh, sorry, Aang. This is more of a two person job." Sokka said quickly. Aang frowned.

Katara exchanged amused glances with Zuko and Azula. Poor Aang didn't understand the meaningful look Sokka was giving him.

"But I feed Appa alone all the time-"

"I think we got this covered," Sokka grabbed Yue's hand and ignored their knowing stares. "We'll see you guys later!"

"So they don't have palaces in the Southern Tribe?"

Sokka laughed, his wobbly watch tower coming to mind. "Are you kidding? I grew up on a block of ice. It's not exactly a cultural hub."

She grinned, her eyes crinkling with amusement, and Sokka struggled not to trip on his feet. He never felt this way about a girl before. His only other experience was with Suki, but their time together was so fleeting; there was no time to get to know her, to have his feelings grow from basic attraction to… whatever this was.

Yue grasped his hand. "Thank you, Sokka."

"For what?"

"For being there for me. Helping me with my engagement, introducing me to your friends, everything." She said softly. "Once I was engaged I gave up hope that I would get to live my life how I wanted to."

"Yue," he said, but he paused for a moment to collect himself. He had never met someone who was so selfless, so courageous. To accept what she must do for her tribe, even when it would make her life miserable- she was braver than she thought. "You deserve to be happy. I would do anything to make that happen. And I know the others would, too."

"I never really had friends before," she admitted. "It's been really nice."

It really was. Their moments alone together were very rare, but it was worth it to see Yue smiling and laughing with his friends.

They reached the stables, which were empty except for Appa. The bison made happy noises as they entered, rushing over to Sokka and licking his whole body.

Yue's tinkling laugh made it more tolerable as Sokka fought to get away from Appa's determined tongue. "Looks like you haven't been giving Appa enough attention," she teased. Appa allowed him to roll away, and when Yue reached a hand out he gave her a very delicate lick.

"Does he really fly?" She asked. Appa nudged her gently, rumbling for pets.

"Do you want to see for yourself?"

He helped her climb onto Appa's head before settling next to her and grabbing the reins. "You holding on tight?" She nodded, looping her arm around his. Sokka felt his whole body flush. "Yip yip."

Yue's gentle hold became a vice-like grip as Appa launched into the air. It was something so mundane and familiar to him now, but he remembered how terrifying it was when he first flew. He wrapped an arm around her as Appa climbed higher into the air. Once they got high enough the ride became smoother, and Yue slowly relaxed as she gazed around, her eyes sparkling and her cheeks pink from the biting wind.

"Wow," she breathed. "I can't believe you do this everyday."

Sokka grinned. "Yeah, we pretty much live up here," he said, stretching his arms out casually.

Yue snuggled closer to him. "Is it always this cold in the sky?"

"Not if you're with someone."

They leaned towards each other, slowly. Sokka gently cupped her cheek as their lips met. Her hands gripped his parka and pulled him closer. For a moment, he forgot the cold. Time itself slowed down. All that mattered was her soft lips and her hands tugging in his hair.

They abruptly pulled away, both of them blushing furiously. Her hands were still in his hair. What were you supposed to do after kissing? The only other kiss he had was with Suki, who left immediately afterwards. That wasn't an option now. She was staring at him, probably expecting him to do something. But he wasn't sure what to do, so he laughed nervously, rubbing the back of his neck.

"That was, uh," he said, too flustered to form a coherent sentence. "That was nice."

"It was," she giggled. She looked so breathtaking, and he still couldn't believe a girl like her would ever want to kiss a guy like him. Yue was a princess, and he was just a guy with a boomerang. He was completely out of his element. Sokka had never felt this way about a girl before. He just felt a pull towards her, like the tides to the moon.

"Yue, I like you a lot." He said, tangling their fingers together. "Like, a lot."

"I like you too, Sokka." She said softly, resting her head on his shoulder.

It was getting colder, the sun lingering on the horizon. Appa grumbled and turned around just as the snow began to fall.

The snow clung to their faces, sticky and heavy and black. Sokka's breath caught in his throat as the flurry thickened, obscuring his vision. They were here. The Fire Nation caught up with them, and by the looks of it they brought a whole armada with them.

"What's happening?" Yue asked.

"It's soot," he choked. "I've seen this before, right before my village was attacked. Soot mixed with snow."

Yue still looked bewildered. "But why?" Of course she wouldn't know, her tribe was never raided like his was.

"It's the Fire Nation. We need to warn the others."

"The day we feared for so long has arrived." Sokka stood with the others as the entire tribe gathered to hear Chief Arnook's speech. "The Fire Nation is on our doorstep. It is with great sadness that I call my family here before me, knowing well that some of these faces are about to vanish from our tribe, but they will never vanish from our hearts. Now, as we approach the battle for our existence, I call upon the great spirits. Spirit of the Ocean! Spirit of the Moon! Be with us!"

Chief Arnook turned to Master Pakku. "I want all our waterbenders at the wall, ready to repair and reinforce it. When they get close, send out small patrols to stall them." Master Pakku nodded. "And Yagoda, we need healers set up on the main level. Have some of our nonbenders carry the wounded for you."

The others began to disperse, directed by Master Pakku and Yagoda, while Chief Arnook approached them.

"What do you intend to do, Avatar Aang?"

Aang looked to the horizon, where the Fire Nation armada would be seen soon. "I'm going to fly out with Appa and try to slow them down."

"We'll come with you," Zuko said. Azula nodded beside him, eager for some action.

"Yes, the Avatar's bodyguards should be with him at all times," Chief Arnook agreed.

There was a moment of silence, in which Sokka resisted the urge to smack his forehead. Zuko coughed awkwardly.

Chief Arnook frowned, but chose not to question them. "Sokka, may I have a word with you?"

He gestured for Sokka to follow him. They stopped at the edge of the wall, where the rest of Agna Qel'a lay below them. The walls looked impenetrable when he first arrived, but now Sokka was not so sure. They were outnumbered. If the Fire Nation managed to breach the walls, then the city would be taken.

"I have a special task for you, Sokka." Chief Arnook said. "I wish for you to protect my daughter."

"Oh," Sokka said dumbly. "Sure. That.. shouldn't be too hard."

"She will be with the healers for now, but if the wall is breached, you must get her back to safety." Sokka nodded, straightening up determinedly. "I trust you with this, Sokka."

"I won't let you down, sir."

Chief Arnook nodded, grasping his arm in thanks. "Princess Yue talks of you often. It comforts me to know that she will have you at her side during the battle." He smiled wryly. "You two spend a lot of time together."

Sokka flushed, rubbing the back of his neck awkwardly.

"You are an excellent warrior, Sokka, and the heir of our sister tribe. I am without an heir, and if I am to die in this battle then it would comfort me to know my tribe is in safe hands. If you wish to marry my daughter, you have my approval."

"Wait, you want me to marry Yue?" Sokka spluttered.

Chief Arnook's brow furrowed. "You do not want to?"

A flash of anger burned in Sokka. Sure, he fantasized about carving Yue a betrothal necklace, and maybe he thought of names for their future children, but if Yue had no say in their marriage then he wanted no part of it. Her father was handing her off to a complete stranger without her knowledge or approval, just like he did with Hahn.

"Chief Arnook, I am grateful for your trust in me, but if Yue is going to marry me then I want it to be for love. It should be her choice."

The Chief was astonished, obviously not expecting Sokka to refuse him. Hahn probably jumped on the chance to marry his daughter.

"That is very honorable of you, Sokka." He conceded. "We can discuss this further after our victory."

Sokka gave a short bow as Arnook returned to Master Pakku.

"Promise me you'll be careful?"

They stood on the main wall, waiting for the attacks to start. The ocean was clear so far, but the black snow continued to fall, a constant reminder of what was coming.

Zuko tried to smile reassuringly. "I promise. We'll be fine."

Realistically, he knew there was a chance that at least one of them was not going to make it out alive. But he wasn't going to tell Katara with her looking at him like that. Her eyes shone with concern, but there was also determination. This wasn't her usual optimism- she was confident in them and their abilities. She really thought they could do this, and Zuko found his own hopes rising as well.

"You need to be careful, too. You're going to be on the front lines when they breach the wall." When, not if. He knew that Zhao wasn't going to settle for a simple siege. He would raze the city to the ground if he could.

Katara nodded. "Come back right away if one of you is hurt," she insisted. Zuko's breath caught as she grabbed his hand. "And don't stay out too long! We'll need you here."

"Okay, okay," he chuckled, squeezing her hand gently.

Something large moved in the corner of his eye. He grabbed Katara as the wall shook from the impact. People shouted as more fireballs began to rain down on them.

"Stop those fireballs!" Pakku ordered, directing the group to grab them out of the air with their water. The wall continued to tremble from the barrage.

Aang hopped onto Appa, Azula not far behind him.

Katara hugged him as he turned to go. "Good luck," she whispered. He squeezed her back, ignoring the chaos surrounding them, realizing that this might be the last time he would see her. She was trembling slightly, her hair tickling his nose.

The wall shuddered again. Zuko pulled away, squeezing her hand one last time, before running to Appa.

Fireballs streaked past them as they approached the ships, Aang tugging on the reins to dodge them. Azula clung to the saddle as they were tossed around, Zuko's hand never leaving her shoulder. One fireball was sent directly towards them. Aang leapt forward, knocking it off course and into the cliffs behind them.

"You ready?" He called back to them.

Azula was more than ready. She was itching to actually do something after being cooped up in an ice hut for so long. Her inner fire was burning hot, eager to be unleashed.

Appa dived. Once they got low enough, she and Zuko jumped onto the ship.

She rolled to her feet, her daggers flashing in her hands. Zuko was right behind her. Azula found herself grinning as they met the charging soldiers head-on, their steel practically singing, their flames roaring with fury This was what she was missing- fighting beside her brother, using her mother's daggers to take down the system that killed her. Every downed soldier was a life saved. Every ship they sank was a blow against their father.

They moved in sync, as if they really were the spirit they mimicked; brutally efficient, quick and deadly, delivering swift justice to each of their victims.

Azula did not feel tired. She did not feel the burns on her arms or the sweat on her face. She only felt the grim satisfaction that came with steel meeting flesh.

Agni dipped in the sky. The fleet released their anchors.

"Zuko! Azula!" Aang swooped down on Appa, blowing the rest of the soldiers off the ship. It wasn't until she and Zuko were back in the saddle that she felt the fatigue in her muscles. Aang looked exhausted as well.

"There's too many," he groaned. "We can't take down all of them."

Azula flicked him on the forehead. He yelped, startled out of his whining. "That wasn't the point," she snapped. "We were just delaying them. They stopped, didn't they? If we did nothing they would have already reached the city."

He took a deep breath, exhaling slowly. "You're right. Thanks, Azula." She stiffened as he wrapped an arm around her. "Let's head back."

The man before him was shivering violently, the helmet rattling on his head from the tremors. Zhao grit his teeth as he was forced to wait for the soldier to stumble through his report.

"It was the Av-Avatar, s-sir," he stuttered. "He had t-two teenagers with him."

"I'm well aware of his companions," Zhao growled. "Tell me something useful."

"Sir, the Avatar c-called them Zuko and Azula."

The room erupted with shouts of alarm and disbelief, drowning out the rest of the soldier's words. Zhao remained silent.

Zuko and Azula. The long dead children of Prince Ozai. The two teens certainly looked Fire Nation, but that would mean that Prince Ozai never actually killed them. Zhao smirked, ignoring his arguing captains. This could work in his favor. If the Prince was hiding this from the Fire Lord then he would certainly go to great lengths to keep it quiet. What could he get out of this? A comfortable estate? Perhaps even a seat at the war table? After this victory, Zhao would have any desire within his reach.

Wiping the sweat from her face, Katara turned to the next gap in the wall. The fireballs were relentless, and she worked nonstop with the other waterbenders to fix the damage. Master Pakku directed them into teams before taking some of the more experienced waterbenders with him to stall the fleet.

It was hard work to fill the walls, but it felt good to be doing something useful. They made the wall thicker as they worked, while others created trenches and single-file bridges across the canals to bottleneck any soldiers if they broke through the wall. She had lost track of how many holes she repaired, but eventually the fireballs slowed to a stop.

"They've stopped firing." Yue and Sokka joined her. The fleet lingered on the horizon, like oil on water.

Appa's familiar rumbling sounded behind them, and Aang slid onto the ground. Zuko and Azula jumped down behind him.

"You're okay!" She rushed forward, giving each of them a quick once-over for injuries. Yue came as well, and began to heal some of Azula's burns. Katara grabbed Zuko's arms and found them covered in small burns and cuts.

"It's fine, really," he said, but he let her heal them without fuss.

"You have blood all over you," she exclaimed, noticing the stains on his clothing. But she didn't see any cuts large enough to produce that much blood.

Zuko met her eyes. "It's not mine," he said quietly. There almost seemed to be a question in his eyes, as if he were waiting for her to reprimand him for killing. But Katara was not a pacifist like Aang was. She was familiar with death. If taking a life was necessary to protect her family, then she would not hesitate to do it.

Katara reached up to wipe off the blood splattered on his face, her fingers trailing slowly over his skin.

"I'm glad you're okay," she whispered. His hand found hers, squeezing it lightly.

"The spirits!" Aang yelled. Zuko snatched his hand back. "Maybe I can find them and get their help!"

"How can you do that?" Yue asked.

"I'm the bridge between our world and the spirit world," Aang said excitedly. "I can talk to them!"

"Maybe they'll give you the wisdom to win this battle."

"Aang, the last time you went to the spirit world was by accident," Sokka pointed out. "How are you going to get there this time?"

Yue's eyes lit up. "Follow me."

She led them back into the city, following a path behind the palace. They approached a round wooden door.

"Is this the way to the spirit world?"

Yue laughed. "No, you'll have to get there on your own. But I can take you to the most spiritual place in the entire North Pole." She leaned forward and opened the door.

Katara gasped as they entered. It was a small oasis, hidden from the rest of the city. A waterfall flowed into a small pool at the center. Aang ran forward and dove onto the grass, rolling around gleefully.

"I never thought I'd miss grass this much!"

She pulled off her parka. "It's so warm here! How is that possible?"

Yue had pulled hers off as well. "It's the center of all spiritual energy in our land."

"You mean this place was here the whole time while we were freezing our asses off?" Azula grumbled. Katara turned to hide her smile.

In the small pond there were two koi fish. They swam in a circle, one always following the other, and Katara found it oddly soothing to look at. The effect was ruined when Momo tried to grab the fish.

Aang closed his eyes and took a deep breath. "I can… feel something here. It's so tranquil." He settled down on the grass, right in front of the pond, and began to meditate.

Everyone settled down as well. Zuko spread out in the grass and flung an arm over his eyes, while Azula took out her daggers and began to clean them. Sokka was picking at the grass absentmindedly. Katara was too restless to sit, so she stood beside Yue as they waited. But staring at someone meditating was boring.

Yue tapped her foot impatiently. "Why is he sitting like that?"

It probably did look weird to someone who wasn't familiar with Aang's spirit world adventures. "He's meditating, trying to cross over into the spirit world. It takes all of his concentration."

"Is there any way we can help?"

"How about some quiet?" Aang burst out angrily. "Come on guys, I can hear every word you're saying!"

They fell silent, which seemed to work because a minute later Aang's tattoos began to glow.

"Is he okay?" Yue fretted.

"He crossed into the spirit world," Katara explained. "He'll be fine as long as we don't move his body."

Katara wondered what help Aang would find in the spirit world. What wisdom could he find that would stop the Fire Nation? Or maybe he could coax a spirit to protect them. They didn't have a lot of time left. Once the sun rose in the morning, the attack would begin again.

The moon shone brightly overhead as they waited.

"I owe Tui my life," Yue said. The moon reflected in her eyes, giving her an almost spirit-like glow.

Sokka frowned. "What do you mean?"

Yue explained how she was saved after her parents placed her in the pond. "My dark hair turned white. I opened my eyes and began to cry, and they knew I would live. That's why my mother named me Yue. For the moon."

Maybe she imagined it, but the moon seemed to shine a little brighter for a moment. Katara hoped that was a sign that Tui was with them.

Zhao smirked as he stepped off of his ship. The city walls were pathetically easy to break through, and now he was closer than ever to making history.

Waterbenders retaliated against the advancing tanks, empowered by the moon above them. His captains clustered behind him, cowering as the battle intensified.

"We'll be following this map to a very special location," he said. "And when we get there, we're going fishing."