Katara flumped down in the snow and heaved a sigh. "Well," she said. "That was disappointing. I bet Zuko's having a good laugh right now. I hope Sokka and Aang got out okay, though." She shook her head angrily. "I can't believe I was so stupid."

Her mother sat beside her and pulled her into a side hug. "Oh, sweetie," she said. "You did the best you could."

"Fat lot of good that did," Katara said bitterly.

"Come on. When you do everything you can, you touch the lives of those around you. It makes all the difference in the world. If it didn't, you wouldn't remember me."

Katara shook her head and leaned back. "That's easy for you to say. You saved my life. Who did I save?"

"Who did you save?" Kya repeated, looking out across the battlefield.

So far north and so close to midwinter, there were only three hours of daylight, after which the firebenders would lose their edge, and the Water Tribe would have a chance to counterattack. Three hours was a very long time.

Dozens of battleships advanced in formation, angling to lob broadsides at the city wall. Blocking was easy enough in a spar, when her opponents threw her own element at her and she could just take control of it as soon as it got closer to her; or even fighting Zuko, whose fireballs had been noticeably anaemic up north. It was a different story trying to catch a two-hundred-pound boulder slathered in burning tar, which melted any ice it hit and disrupted her control; and it was still another when the Fire Nation started using some new kind of projectile that turned into molten iron and slag mid-air, flash-boiling anything in its path. Waterbenders dashed back and forth, trying to plug holes as fast as the bombardment could make them. It was a losing fight, and worse, the wall was starting to creak ominously: sooner or later, they'd pull too much ice out from one part to put into another, and the whole thing would collapse under its own weight.

Katara swept a column of water into the path of a boulder and froze it, while Aang airbent a gust into a ball of liquid iron. It splattered apart and droplets splashed the upper lip of the wall, spraying steam.

"It's no good!" Aang shouted over the din of battle. "I'm going in!" He snapped out his glider and took off toward the fleet.

Katara nodded, out of breath, and surfed up onto the wall.

"It looks like you fought bravely to protect your people," Kya said.

"Yeah," Katara said, inspecting the fleet. She hadn't really thought it through in the heat of battle, but the ships were specialised. There were gunships covered in catapults, pounding the city wall; troopships with armoured prows, packed with marines; and smaller, faster cruisers with depth charges, which they'd used at one point to zone out a team of waterbenders who'd tried to counterattack from underwater. Aang was approaching a gunship, probably reasoning they were the main threat. "I know, Mom, I tried. But the Fire Nation …"

There was a moment when Aang had to slow to a stop to land safely: a platoon of Yuyan archers stepped out of hiding and loosed a volley at him point-blank. Katara winced. From this perspective, it was painfully obvious they'd been waiting for him. Aang spun his staff, doing she couldn't even imagine what to the air currents; most of the arrows corkscrewed into the ocean, but there were trick arrows there too with bolas and weighted nets, which tangled round him and slammed him to the deck.

"… is smart enough to keep doing what works," she finished.

She joined in with a hundred Water Tribe benders and warriors, led by Pakku, as they blasted out through the wall and ice-surfed toward the ship. Its engines roared to life, reversing away from the wall, while its cruiser escorts accelerated forward to intercept the warriors. Pakku traded shots with the cruisers, while the other warriors boarded the gunship. Marines swarmed to engage them, and a melee broke out, fire against water.

"Well, you're smart enough to know that you have to protect the Avatar," said Kya, watching Katara freeze water around the legs of an armoured firebender and a big soldier with a spear.

"We were lucky," Katara said. Warriors sprinted forward to cut Aang free, and he air-blasted a line of soldiers overboard. "If those other cruisers had been just a bit closer, we wouldn't have been able to reach Aang at all, and Zhao could have just taken him and left."

"Still, you saved him."

"For now."

A troopship pulled alongside the gunship and threw down landing ramps, and hundreds of marines flooded over. Katara and Aang threw a few more defiant attacks at them, but there was nothing for it but to fall back to the wall. Breaking formation to rescue Aang had cost them: dozens of Water Tribe warriors were caught, and the wall had a gaping hole in it. Waterbenders were running over to close it, but Fire Nation troopships were closer: they crunched straight through what was left of the wall, and soldiers poured out into the city.

Katara and Aang fought desperately, but they were too badly outnumbered, and the Fire Nation artillery wasn't letting up. For every soldier they knocked down or out, they had to dodge or deflect a volley of flaming boulders, and then three more would take his place. As she half-blocked another molten slag round, a siege crossbow bolt slammed into the wall over to the west, sending spiderweb cracks running down it, and another troopship accelerated into and through it. More marines jumped off and into the battle, brandishing weapons or throwing fireballs.

Katara grabbed Aang and pulled him back. "Aang – this isn't enough. You have to use the Avatar State."

He hesitated just a moment, then nodded and shut his eyes. And then nothing happened.

"That reminds me," she said. "If you're a spirit now, do you know why it didn't work?"

"It's not my place to say," said Kya. "But the Avatar is a great and mighty spirit. It doesn't take orders from humans. It has its own wants and needs, and those aren't always what we want or need. It might help you sometimes, but you shouldn't depend on it. Depend on Aang, and Sokka, and Zuko, and yourself."

Katara nodded, although privately she thought that she'd have to make some very poor decisions to wind up in a situation where she should depend on Zuko for anything.

Aang gave her a desperate look. "It isn't working," he said. "Why not? It's supposed to happen when I'm in danger. How much more danger does it want?!"

She chewed a knuckle. "I don't know. I don't know, but – the Avatar is a spirit. Maybe another spirit would know. Like at the Spirit Oasis."

He blinked and gave a little smile. "It's worth a shot. Come with me?"

She glanced back at the battle. "No. I need to stay here. I'll help hold the line for as long as I can."

"I can't leave you!"

"I'll be okay."

"But –"

"We don't have time! Go!"

Aang gave her one last look, then turned and ran off.

She looked back to her mother.

"Well, you tell me. Did I save him?"

"He's alive," Kya said. "That's all anyone can hope for."

"… Why did you have to die, Mom?"

"Well, it was a bit of a nasty shock for me, too," Kya said wryly. "I thought I'd be captured, and either I'd break out or Hakoda would save me. But, still, even though it didn't quite work out that way, if I had the choice, I'd do it again. It's a mother's duty to protect her child. Her duty, and her joy. You've made me proud."

"It was so hard to go on without you."

"I know, sweetie. I'm proud that you did, anyway. Coming all this way to learn to waterbend? You're so brave, Katara."

"Will they be able to go on without me?"

She joined the line of warriors trying to push the Fire Nation beachhead back. She swept ice up and forward, knocking the soldiers off their feet, but they'd already done their job: buy enough time and space for the ships to unload a line of tanks and rhinos. They surged forward, spraying fire and bowling the warriors over, immune to everything but the heaviest waterbending attacks. Behind them, more troopships smashed through the wall and unloaded still more soldiers and heavy gear. Katara fell back, throwing everything she had at them.

After fighting her hardest for over an hour, she was getting tired and sloppy. She looked up too late to see a flaming boulder as it arced up, down, and crunched into her.

Kya winced sympathetically. "You really have to take better care of your looks, Katara," she said.

Katara chose to ignore this.

"Such a stupid way to go," she said, watching the boulder roll off her and into a canal, leaving a trail of burning slime. "At least you died a hero. I was an idiot who didn't pay attention. I hope Sokka and Aang don't see me like this. … Do they?"

"You don't get to know that until you die, sweetie."

"Am I not?" She indicated her body: squashed and on fire.

Kya smiled and twirled a finger, 'Turn around'. Katara did: Zuko was loping up. Seeing her, his mouth fell open, his good eye wide. He brought his hands together and inhaled sharply, and the burning goo on her went out.

"Aren't you supposed to be under house arrest?" she asked.

"Did you really think that would stop him, sweetie?"

"I suppose not. Hey, what d'you think you're doing?!" she added to Zuko, who'd scooped her up into a bridal carry.

Kya snickered. "I like him."

"Spend an hour with him. He wanted to leave this entire city for Zhao!"

"It hurts the most when someone you should be able to count on lets you down," Kya said wisely.

"Why would I be able to count on someone from the Fire Nation?"

Kya shrugged, still grinning. "Your destinies are intertwined," she said. "It's up to you to decide what that will mean, but I have a good feeling about it. Good luck, sweetie!"

Zuko took off at a run, away from the battle.

"Wait! Mom! I don't –!"

He rounded a bend, and her mother was gone.

He dashed around the city, dodging slickly coordinated Fire Nation columns and desperate waves of reinforcing Water Tribesmen, until he reached the hidden portal to the Spirit Oasis. He kicked it off its hinges and walked in.

Aang sat in meditation by the pool, his tattoos glowing, presumably off on some sort of Spirit World Avatar quest. Sokka and Yue were with him, talking in undertones. Seeing Zuko and the body in his arms, they broke off. Yue's mouth fell open, and she took a step back; Sokka's hand went to his hatchet.

"What are you doing here?" he asked.

"Water-healing," Zuko said, walking forward.

"There are healing huts."

He stepped up to the pool and laid her in, very gently, making sure as much as possible of her body was submerged without drowning her. A cloud of soot, slime, and other battlefield filth began to wash off her and foul up the pool; but at the same time, almost imperceptibly, the water glowed around her. If Tui and La were affronted by this, they didn't show it: they just kept circling each other. "Not for long. Besides, water-healing is a spiritual art, and this is the spiritual heart of water. This is where she belongs."

Sokka finally recognised her, and his face fell. "kAtaRA?!" He rushed forward to cradle her head, Yue a pace behind. "No – what happ– … ?"

"Exactly what I said would happen," Zuko said. "Listen. Can you call the bison from here?"

Sokka looked from Katara to Zuko, back to Katara, to Aang, and back to Katara. "But … I can't leave her …"

Zuko took the bison whistle from Aang's neck and blew as hard as he could, then tucked it under his yoroi. "You won't," he said. "This is the last time we'll see each other. I'll get the Avatar out of here. You stay here and watch over her. When Zhao's men come, don't try to fight: the Fire Nation military has standing orders that anyone who surrenders honourably is to be offered medical care. It's her best chance, if the water doesn't work. … Take care, Sokka. And you," he added to Yue, "should surrender personally. Spare your men. When Zhao captures you, the battle ends."

"Does it, now?"

Zuko froze, then rose, turning to face Zhao. He hadn't come alone: half a dozen armoured firebenders flanked him.

"Zhao," Zuko spat. "Prance off. The Avatar's mine."

"Your what? True master?" He tsked. "Here was me thinking you fell down a mine shaft somewhere. I never would have guessed you would have turned traitor. Cavorting with a Water Tribe peasant, trying to rescue the Avatar, again …"

"I'm no traitor, Zhao."

"Your father, on the other hand? He guessed. We've exchanged some very interesting letters, little Prince."

Zuko's fingers twitched. "I spared your life once, Zhao. I was in a good mood then. Now? I've been having a day."

"Terrifying," Zhao said. "Well, if you think you can back those words up, come on. Or you can hand over the Avatar and surrender, and hope your father takes enough pity on you to spare your life again. Or we can stand here. I have all the time in the world. It won't be long before reinforcements arrive."

Zuko sunk into a martial arts stance. Zhao and five of his soldiers mirrored him. The sixth hesitated, then lifted a single finger, Wait one moment, please, and took off her helmet and tossed it aside.

Zuko's mouth fell open and he straightened. "Azula?!"

She bowed and gave a sardonic smile. "Hello, Brother. Long time no see. Hello, Admiral. Terribly sorry I didn't introduce myself earlier. It didn't seem quite the time."

"Princess," Zhao growled. "What are you doing here?"

"An errand for Father," she said. "He wants the Avatar, and he wasn't confident either of you would deal with him properly."

"I was going to!" Zuko said.

"No, I am going to," Zhao said. "He's right there."

"So he is," she said. "And so he was, at Pohuai. You only get one humiliating failure of that scale per lifetime, Admiral."

"That – your brother broke him out!"

"That's a bold accusation to make," Azula said.

"No, I didn't!" Zuko said at the same time.

"And really, not a very impressive defence," she went on. "An entire army under your command, and yet a single unsupported teenager plucked the Avatar out from under your very nose? If I let you drag him off again, I expect nothing short of some well-placed thumbtacks will thwart your plans this time."

Zhao flushed angrily. "I can do this."

"That's very life-affirming, Admiral, I'm happy for you. However, I had a second task, too: assist Prince Zuko."

She stepped and pivoted, putting herself shoulder to shoulder to Zuko, whose face went from desperation through astonishment to an ear-to-ear grin.

"Yes," he said.

Zhao gaped. "He's committing treason right in front of you! If your father were here, he'd execute him on the spot!"

"It's not an Admiral's place to second-guess the Fire Lord, or even a Princess's," said Princess Azula. "If he wanted his son dead, he would have killed him three years ago. The Fire Lord told me to ensure my brother's safety, and I know how to follow orders. No matter how irritating it might be to be Little Zuzu's subordinate," she added. "Still, any further details can be resolved by the Fire Lord himself, once he is presented with the facts. Don't you agree, Admiral?"

Zhao clenched a fist. "No, Princess," he said. "I think my duty is to stop high treason. Maybe you're hoping to get the throne early? Or maybe you have some other plan in mind. But whatever it is, I am going to bring the Avatar, your traitorous brother, and the boiled corpse of the Moon Spirit to the Fire Lord, and if you want to join them, then be my guest."

"Oh, is that the Moon Spirit?" she said, glancing over her shoulder at the koi fish, circling beside Katara. "And the Ocean, I presume? I'm curious about why you'd pick these of all spirits to try to kill."

At that moment, Appa swooped down and hovered thirty feet above Zuko. He looked around, rumbling suspiciously.

"… but not curious enough to stick around to find out," Azula finished. "It's time for us to leave, brother."

Zuko took a step toward Aang, but Zhao shot a fireball at Appa, who roared and shot back upward and out of sight.

"It's time for you to surrender," he said.

"You want to go?" Zuko said, moving into an offensive stance. Smiling, Azula mirrored him, and Zhao and his men assumed guard stances. "Then let's go."

They stared each other down for a long moment, then the Spirit Oasis burst into flame.

It was six against two, but from the intensity of the attacks, one would have thought it was six against ten. Zuko and Azula criss-crossed the clearing, bending flowers of fire between the ranks of the enemy benders. Zuko's signature spin kick could engage the entire platoon at once, and Azula's bright blue flames sliced straight through every attempt to block, sending men flying. The five armoured benders went down in under a minute. Zuko jump-kicked Zhao in the chest and knocked him over, landing on top.

"Now," Zuko growled. "I'm not going to tell you again. Stay out of my way."

Zhao sneered. "If you're going to go full traitor, then kill me now. Because I would rather die a hundred deaths than embarrass myself like you."

Zuko snarled and bent a fistful of fire, but he didn't throw it. Zhao smirked.

Azula's eyes gleamed. She walked over.

The sun had been too low in the sky to reach into the Spirit Oasis. Now, it crossed below the horizon, and even its diffuse light faded out, leaving them in twilight.

Zhao's smirk evaporated, and his eyes widened. "Zuko," he said quickly. "She's not a traitor. Your father –"

Azula roundhouse kicked Zuko in the jaw, sending him skidding across the clearing. Then, with a burst of brilliant blue fire, she brought her boot down on Zhao's head in a full power axe kick.

"Nothing personal," she said.

She glanced at Zuko – unconscious but alive – to Aang – still sitting cross-legged, deep in the Spirit World – to Sokka, whose eyes widened. He glanced around, looking for cover; she shot fire to his right, forcing him left, then to his right, forcing him back, then landed a blast square in the centre of his chest, knocking him down and out.

She took a moment to confirm he wouldn't get back up, then returned to Aang. She made strange circular motions with her hands, and crackling energy followed behind, splitting into arcs of light that tore air itself apart. Then, she unleashed a blinding white beam straight at him.

A bulge of ice rose to block at the last moment, absorbed the lightning bolt, and burst into a spray of steam and tiny ice shards. Static electricity crackled into the ground, and there was a pulse of heat and humidity as it dissipated through the ground water.

Azula harrumphed and turned to the newcomer. "Do you people not understand what's going on here?" she asked. "I don't mind killing everyone who gets in my way, but I would have assumed that at least one of you would."

Pakku stepped forward, gesturing, cooling down the pool. "This is the most sacred site to all of waterbending," he said. "I would spare it the sacrilege of more death. Go, and enjoy your victory elsewhere."

Azula raised an eyebrow.

"I'll get right on that," she said, drawing the jagged white circles again.

Pakku gestured, and an iceberg folded out from the surrounding glacier; she dived out of the way, blasting it with blue fire, but he just let it roll forward and squash her. He turned to the pools, clapped his fist against his open palm, and offered a bow of apology.

Yue ran out past him. "Sokka? Please be okay, please be okay …"

"Nngghhaaahahaaah," Sokka said. "Yeah … never better …" He tried to get up, but couldn't.

Pakku glanced at Zuko, and his expression hardened. Then he looked back to Katara and shook his head. He gestured, gathering the crud that had washed off her into a water ball and depositing it in a pile beside Zuko. "Princess," he said. "Thank you for warning me, but I must return to the battle. With Zhao gone, perhaps we have a chance. Watch over the Avatar." And he ran off.

There came painful coughing from the pool.

"Katara!" Sokka said. "Are you okay?"

Katara's skin was solid bruise and blister where it wasn't still covered in tar, most of her clothing had burned or melted off, she had a killer headache, and this had to be what broken bones and internal damage felt like.

"I'm fine," she said.

"Can you heal?" Yue asked. "Sokka's hurt."

Regretfully, she pulled herself out of the pool, tightened her wrap around herself, and limped over to Sokka. She wasn't sure which of them had it worse. His parka and shirt disintegrated at her touch, and the skin underneath made Zuko's scar look like a cute sun tan. She pulled handfuls of water from the pool and set to healing, working on both him and herself at once. Sokka let out a whimper of either appreciation or protest, she couldn't really tell.

Kind of regretting not spending more time practising healing now.

Don't tell Pakku. Anyway, if we had, we wouldn't have lasted as long in the fight, and Aang might have been caught instead.

Zuko stirred and let out a moan. Yue hesitated, then walked over.

"Relax, Prince," she murmured. "You're safe."

"Whrr – rr, whrr hrr?!"

"Don't try to talk. You're too hurt."

He rolled onto his side, so that he was facing toward Azula.

"Rrr! M' srrrr!"

"She just tried to kill you, and Aang, and me," Sokka called, then coughed.

Zuko grabbed Yue's wrist and jabbed a finger at Azula. "H'rr hrr!"

"You – okay! Just let me go!"

Yue hurried over to Azula, dug out enough ice that she could breathe, then returned to Katara and Sokka.

"What do we do now?" she asked.

On cue, Aang woke up.

"Guys!" he shouted, panicking. "Zhao's coming to kill the Moon Spirit, and …" He looked around: the once-pristine clearing covered in scorch marks, Zhao, Azula and a handful of firebenders unconscious, Zuko badly hurt, Sokka badly hurt, Katara –

"Uh," she said, watching him take in her injuries.

His eyes and tattoos lit up. He walked into the pool, and what walked out wasn't even close to human.

"Whrr?!" Zuko cried out, trying and failing to get to his feet. "Nnn –!"

Yue tackled him to the ground, and the spiritual presence swept past.

9