"I've been saving it for something important." She said slowly, looking back up at the face of the enemy.

She managed not to flinch when his eyes narrowed at her searchingly, and simply held the vial of oasis water between them. Without saying anything further, she reached for his face. The left side.

The scar tissue was a strange mixture of texture. She'd never gotten so close to long-healed burn scars before. The skin moved loosely beneath her touch, but the bumpy tissue beneath it remained stiff and unmoveable. Zuko's breathing seemed harsh and shaky, but his face managed to remain impassive.

"But…" She pulled her hand away. "I only have enough water for one attempt. It may not even work…" she trailed off, feeling uncertain, but he was watching her again and the sense of empathy, of strange camaraderie, that she's started feeling when he mentioned his mother's loss grew. "But I'll try."

Zuko's face was still strangely rigid, but his eyes kept flickering around the room, looking panicked and young. He managed a quick, jerky nod, and Katara swallowed hard. The glow of the crystals in the cave gave his pale face a sickly look, and the dark, clumpy scar seemed to reflect the light back at her, shiny and unnatural.

Hurrying a little, as the fire princess could return at any time, Katara opened the bottle with an impossibly loud pop and summoned the oasis water to her hands. "You probably want to close your eyes." She prompted him, but his eyebrows came down in almost a scowl.

"No thanks." He rasped. "I don't… uh. I'll keep them open."

Taking a deep breath to get rid of the bristle of annoyance, Katara raised her hand to the left side of his face again. With one hand nearly covering the scar completely, she could kind of see what he'd probably looked like before whatever gave him the original wound. His mouth was set in a nervous, firm line, and his eyebrows were down. Almost a glare except for the wider yellow eye looking back at her, with its terrified, tiny pupil.

Younger than she'd thought. And he looked somewhat less royal to her without his main distinguishing feature. Kind of handsome but he could be any Fire Nation boy in the world without that scar.

"I can't feel anything." He whispered, almost stuttering.

She put her left hand on his other cheek, to keep him still. "I've not started yet. I'm trying to figure it out."

The water fell between the creases of the scar, glowing as it penetrated itself into the tissue of his eye socket. Focusing now on the task at hand, Katara barely registered the change of expression, only tightened her fingers on his face to keep him from moving away.

The spirit water seemed to fizz under her fingers. It felt so different from her other healing efforts and it seemed to have a mind of its own, fizzing and sparkling and dancing beneath her hand.

The water was sinking into his flesh, and she hoped there would be enough. She could feel it restoring and plumping up the burned away parts of his face, and it made his whole body shake under her hold. When the water was all gone, and her hand felt skin on skin, he was still shaking.

She didn't move either hand and let out a long, controlled breath. "Are you ok?"

He raised a hand to touch his face, but only catching the back of her hand. He flinched slightly but stopped shaking. Wordlessly, they looked at each other, wide-eyed and wary.

They were suddenly engulfed in a cloud of dust and rubble. She turned to see Aang and couldn't help but run over in a tangle of arms and laughed with relief.

She managed a quick peek over towards Zuko, but his face was turned away from her, and he looked as though he was trying to squirm out of his Uncle's grasping hug. She still couldn't see if it had worked.

"Uncle, I don't understand. What are you doing with the Avatar?" Zuko sounded strange, and as Iroh pulled away from him, Katara was a little frustrated that she could only see his right side.

Aang bristled and pulled away from Katara. "Saving you, that's what!"

Iroh turned to Aang and Katara, with a smile. "Go help your other friends. We'll catch up to you." Zuko glanced her way but turned quickly before she could see.

Her heart sank. She must have failed. The spirit oasis water hadn't been able to heal his scar and she'd wasted it on someone who wasn't even on their side.

Aang pulled her along towards the tunnel. She paused at the mouth and turned back to look at Zuko, who had his back to her and his fists clenched. She didn't really know what to say, and Iroh was looking back to him and saying something in a low voice, hands on his nephew's shoulders. She felt wrong, voyeuristic.

So without anything else to say, she followed Aang into the tunnel.

They'd just reached another glowing cavern when Aang suddenly turned and threw up a wall of earth to deflect the flash of blue at their backs.

They were under attack from the rear. Katara's mind cleared and she instinctively reached for the water in the underground canal, dragging a wall of water towards the fire princess. She was wearing earth kingdom clothing and looked a little wild as she steamed away Katara's attack with a huge wall of blue fire.

Leaping through the cloud of dust and steam, she punched two fireballs at Aang and Katara, who moved in unison to block them with more water. Heart pounding, Katara looked up to see Azula smirking, perched on one of the cave's supporting rock columns. Beside her, Aang moved into another earth bending stance and broke it apart.

They had the satisfaction of hearing Azula's gasp as she fell, but she managed to push herself off and landed on her feet.

Right between Katara and Aang.

All three froze. Azula had her arms outstretched, pointing at each of them. All three were panting a little, sizing each other up. Katara and Aang focused on Azula, who glanced between them with wide eyes.

Katara's heart pounded and stuttered as a red fireball came hurtling through the tunnel and landed between Aang and Azula, causing both to jump away.

Katara squinted through the smoke and debris to see the familiar figure of Zuko in a firebending stance. He glanced between the three of them and Katara's eyes widened as he met hers. His face- it was-!

Azula yelped in surprise as Iroh seemed to melt from the shadows and sent a torrent of flame her way, she skirted the edges of the stream of fire and rebounded off another column of rock Aang sent her way.

"You!" She gasped, eyes wide and furious at Zuko. "You fool, have you any idea…"

Iroh sent a fireball hurtling at her, cutting her off. She turned wildly, and Katara was reminded of the last time they'd faced Azula, in the Earth kingdom village when Iroh had been struck by lightning.

It appeared as though Azula was thinking along similar lines, as she circled her arms and summoned vivid white-blue sparks into her fingertips, just as Katara's water closed over her.

It wasn't intended to knock her off her feet, just capture her hands, but water conducts electricity, and the baby sparks of lightning charged through the water and Azula jerked with the force of it before her head dropped back limply as the water splashed away.

"Azula!" Zuko shouted as she dropped to the floor, but Aang lifted a barrier between the siblings, watching Zuko with narrowed eyes.

"What happened to your face?" He asked coolly, and with two quick stomps of his feet, the other boy was rooted to the spot. Iroh, who could still move freely, held up his hands and approached Aang with a peaceful expression.

"My nephew and I would like to join you, and there is much to discuss… but perhaps now is not the time." He looked calm, but there was an edge to his voice that caused Aang to nod, and after a moment's hesitation, release Zuko.

"We have to get out of here." Aang agreed. "Do you think she'll be alright?"

Whatever had made Zuko attempt to run to her before wasn't there now. He looked over to the still form of the fire princess with a blank expression that made Katara feel cold. "She'll be fine." As though she'd heard her brother's voice, Azula stirred. Zuko's expression snapped to one of mild panic. "Let's go."

But at that moment Iroh seemed to perk up at something neither Katara or Aang could sense. "Oh dear.."

"Azula always has a backup plan," Zuko muttered grimly. "We already caught her off guard earlier."

What felt like hundreds of Dai Li agents seemed to appear from the darkness of the tunnel. Katara took a step back but gasped in realisation as she saw they were behind her too. She readied an octopus of water whips around her and turned so she was facing outwards. Aang, Zuko and Iroh, she knew, would do the same.

They were nearly back to back, in a tight circle. A couple of Dai Li agents crouched by Azula, rousing her. It hadn't been enough of a charge to put her out for good, Katara knew, but she'd hoped for more time. Flickering golden eyes cracked open and glared at their group.

Not their group, Katara realised with a start. Not even Aang.

Just Zuko.

"She's probably going to come for me," Zuko muttered quietly. "You guys can focus on the Dai Li."

"Remember what I taught you, nephew," Iroh said gently, under his breath. "Follow your energy pathways. Fluid like a waterbender."

Katara couldn't risk a glance back at them, but she frowned in confusion. Them the Dai Li struck.

They were totally on the defence, Katara was batting rocks out of the air, but the ground beneath her was rocking, and breaking her stance. She tried to solidify the ground beneath them with ice, and she could feel Aang beside her doing the same with a combination of water and earthbending.

Iroh and Zuko were providing the bulk of the attack power, sending flames powering into and licking around the defensive rock barriers of the Dai Li, they were just about holding them off, and knocking a few agents back but the familiar blue crackle in the air told her that their barely held advantage was fast fading.

"Aang. You mastered the Avatar state, right?" She hissed, breathless from the exertion. She didn't like it, but presumably, the Guru would have given Aang access to the terrifying, powerful connection he had with his past lives, and it was sure to be helpful against the Dai Li if only to help them escape.

"I'm sorry Katara," Aang whispered, and stepped away, bringing up some more of the green crystals to enclose him inside.

Sorry? Why was he sorry?

"What the hell is he doing?" Zuko shouted, punching fireballs towards the Dai Li as they attempted to fully rouse Azula. She was blindly throwing blue fire around her, catching several agents in her daze.

"He's going to help!" Katara shouted back, narrowing her eyes. "We just need to hold them off a little longer."

But they didn't have long. Azula was coming to properly, and the Dai Li were covering her as she shakily prepared a blast of lightning again. Katara tried to look, but the Dai Li were strong, and the barrage of boulders and columns was as overwhelming as she could bear.

Her hair had come loose at some point, and it was blocking her peripheral vision, meaning she had to turn more to spot the crashing rocks and constant barrage. There was so much earthbending happening that it felt like the whole cave complex was about to come down around them.

Azula let out an angry cry and released the lightning at Zuko. Katara tried to send a wall of water to block it, but she was distracted and had to bring another wall up to prevent bullets of crystal fragments from catching her, but she felt small pieces rip into her right leg, which wasn't properly protected. She tried to hold proper form but the Dai Li were master earthbenders, and she was outnumbered.

Zuko was outclassed.

But the lightning seemed to get swallowed up and spat back out. He'd sent it back at her in a move she could have sworn looked like waterbending…

Azula's surprised face was illuminated by a sudden burst of light from Aang's hideaway. The crystals cracked and the Avatar floated slowly into the air. Katara smiled with exhausted pride and the Dai Li stared up in amazement. As everyone else was momentarily distracted, Azula ent a quick blue fireball straight at Aang's chest.

Aang seemed to absorb it, before lifting his arms and causing the whole cave to shake. Power surged through the air in awful, pulsating waves. There was a great rumbling, and Katara fell to her knees with her hands over her ears. It was so loud, and the weight of the earth above them felt so heavy and oppressive.

She squinted up at Aang, who was still in the Avatar state. She tried to shout to him, but her voice was lost in the roar. Rocks fell between them and the Dai Li, who were scrambling to retreat even as Azula glared upward, unmoving as the cave collapsed around her.

Iroh took hold of Katara's arm and tried to shout something, but Katara couldn't hear. Zuko seemed to be lost in his own thoughts, watching his sister, but Iroh grabbed him by the shoulder too and dragged them away, towards the waterfall at the far side of the room.

Aang followed them, still floating and pulling the cave apart. Looking up, Katara could see a glimmer of the sky at the top of the waterfall and pulled the water to bring them up. They came up somewhere behind the palace, and Aang appeared shortly after, seeming himself again as he reached for Katara's wrist with a determined frown.

"We have to get to Appa."

"Sokka and Toph will hopefully be there." Katara agreed, helping him to his feet. He was a little shaky but nowhere near as exhausted as the Avatar state usually left him. "If not, we're not leaving without them." She smiled, but Aang simply nodded.

The streets were relatively free of the Dai Li as the group raced through. Nighttime had settled, and Katara felt her blood charge with the moon, helping her react quicker, more accurately to the few threats they encountered.

Thankfully, Sokka and Toph had orchestrated their own escape and were preparing Appa for takeoff as they arrived. They had the Earth King and Bosco with them.

"Sokka!" Katara grinned, grabbing him in a tight hug. "Toph! I'm so glad you're ok."

"You too. We were trying to figure out how to rescue you… wherever you were." Sokka grinned, before looking over her shoulder. "Who-" he froze.

"They're with us," Aang said quickly, to Sokka's twitch of recognition. "Iroh and Zuko are coming with us." He leapt up onto Appa and Katara pushes Sokka ahead, not allowing whatever protest was brewing beneath his increasingly purple face. "We can discuss it later but we have to go."

"They're coming." Toph hissed, eyes widening. "Come on old man." Iroh nodded and clambered up after her. Zuko eyes the bison warily, but Appa seemed to muzzle toward him, giving him an affectionate lick.

"Right. You again." He muttered, but he looked up to his uncle and climbed into the saddle anyway.

As they took off into the night sky, leaving Ba Sing Se behind them, Katara cuddled Momo to her tightly and idly toyed with the glass vial that lay empty around her neck.

She'd done the right thing by healing Zuko… right?