"Masking energy is about control," Yuzo explained, walking with Zuko along the deck to find a space where they could train. "You can feel your inner fire now, right?"

Zuko nodded.

"Well, this technique is all about keeping that fire low. Energy sensors pick us healers out from a crowd because we look brighter to their mind's eye. Keep the flames low and—"

"We won't stand out."

"Exactly." Yuzo stopped and looked at him expectantly. "Let's see you try it then."

Zuko exhaled and closed his eyes. His inner fire was as strong as ever: warm, vibrant, and within it the golden sphere of flames hummed with power. But it wasn't a real fire. It probably couldn't be bent like one either. This sphere of heat and light was a heartbeat of energy, a source of life flowing through him. It gave breath to his fire, it was the source of his fire, but it was still pure chi at its core.

How was he supposed to suppress his own chi? He knew how to direct the flow and use it for healing, but supress it?

"Have you got it?" Yuzo asked, though his tone was more impatient than encouraging. "I can't sense energy, remember, so you'll have to tell me what you feel."

Zuko shot him an irritated glance. "You haven't exactly been forthcoming with tips. It's not like this is a campfire I'm trying to control."

"You're the one who's supposed to be a natural."

A flat look.

Yuzo's mouth twitched. "Alright, alright." He moved closer. "Don't be intimidated by the fact you're working with energy instead of fire. The fundamentals are the same. You just have to assert your willpower over it and get your inner fire to do what you want."

"Simple as that, huh?"

"Surely you've heard the saying: willpower is the foundation of firebending. If you aren't willing to master the flames, they'll control you. It's no different for bending energy. How else do you think you've been able to heal people? It's because you willed it to be so. You willed your energy to join with theirs so they could be healed." Yuzo folded his arms across his chest. "I thought you knew all this stuff."

"Most of what I've done has been instinct," Zuko admitted.

Yuzo's eyebrows tried to vanish into his hairline. "Maybe you are a natural. You're lucky you're not dead with all the healing you've been doing."

"So people keep saying …"

Yuzo considered him for a moment, then shrugged. "Whatever. Give it a shot. Focus on your inner fire and bring it down like you would flames you want to weaken."

Zuko nodded and once more closed his eyes. It was as simple as breathing to connect with his inner fire. It always had been. Even if he had discovered his bending far too late for his father's tastes and had struggled to master the basics, he had always felt a strong connection to his element and the chi within him. That was why healing and redirecting lightning had come naturally to him. Energy—the power he manipulated inside his body rather than outside—just made sense. It spoke to him in ways that offensive techniques and streams of fire had never done.

That instinct also kind of made sense now.

He had never wanted to hurt people. He had never wanted to burn or kill, not even when desperate to capture the Avatar and return home. But that was what traditional firebending had been all about: hurting, making war. It was no wonder he had struggled for so long. He had been going against his nature just trying to live up to what the Fire Nation and his father expected from him.

"Did you do it?" Yuzo asked.

"Give me a moment."

Zuko inhaled a deep breath before exhaling and willing the fire within him to shrink. It felt … weird. Really weird. If he was to think of it in a physical sense, it was a bit like trying to drain all the power from his muscles. His inner fire fuelled his bending, his strength, and he was intentionally smothering it. All that humming force of life, all that vibrancy and warmth, it all dwindled down, down, down …

Splotches and stars danced before his eyes. A high-pitched ringing reverberated in his ears and he swayed.

Yuzo gripped his shoulders. "I think we can safely say you're getting the hang of it."

"A warning about the side effects would have been nice," Zuko gritted out. His head was still spinning.

"At least I didn't let you fall on your face."

Zuko glowered up at him. "Just tell me how to make it stop."

At this rate, he was going to end up vomiting all over the deck.

"There really isn't an easy way. Your equilibrium has been thrown off and all you can do is hope your body will adjust."

"Are you kidding me?"

"I mean, you could try easing up on your inner fire, but that puts you at risk again." Yuzo looked him up and down. "To be honest, if you're having such bad side effects, you probably do need to keep your inner fire as weak as possible. Shen said that the more powerful benders tend to feel it the most when they supress their chi; obviously, they're also the ones who burn the brightest."

"Yay for me."

Yuzo actually laughed, though his amusement faded a second later. There was an old ghost lurking in his eyes.

"What?" Zuko said while slumping ungracefully into a sitting position. His legs felt like wobbly jelly.

"It's just …"

"What?"

Yuzo looked the other way. "The last person I taught this technique to was Atsuo …"

Zuko let out a breath. Oh.

"He never really got the hang of it. I practiced with him all the time, but …" Yuzo's voice thickened. "He wasn't a natural like you. That idiot burned too bright, but he was terrible at controlling his inner fire. Wasn't even a good bender, really."

"Is that why you told him to run?"

Yuzo nodded. "I didn't want him to get hurt. I thought if I could just give him enough time to get away, then …"

A long hush of silence.

"It's not your fault, you know," Zuko said a bit awkwardly. "You did everything you could."

"But I didn't! I should have been there for him, should have found him faster!"

"Would it have really made a difference?"

Yuzo's jaw tightened.

"I don't mean to be blunt, but it sounds like you would have both died had you been with Atsuo. You barely survived your last encounter with your brother, right?"

"Half. Half-brother."

"Right. Sorry."

Yuzo kept his face averted. His hands were balled into tight fists.

Zuko regretted saying anything now. He wasn't good at this emotional stuff. It was just really obvious that Yuzo was hurting, and the healer in Zuko couldn't help wanting to make it a little better. Too bad all he'd ended up doing was putting his foot in his mouth.

The silence dragged on.

"I would have died for him," Yuzo eventually said, so soft it was more an exhalation of breath. "I would have died with him if it had come to that. Don't you get it? I loved him."

Zuko's eyes widened a fraction.

"But he's dead now, and there's no doubt in my mind it was Shen who killed him." Yuzo turned his head to meet Zuko's gaze, his expression hard yet intense, like a blazing stone. "The Silencers have taken everything from me. They'll take everything from you as well if you let them. That's why you'd better do everything you can to make this technique work for you, no matter how unpleasant. It might be the only thing that saves the ones you care about."

oOo

"Why the glum face, Twinkletoes?"

Aang scrunched his nose. "Glum face? You can't even see my face."

"Don't have to." She poked him with her foot. "Your whole body is screaming glum. You're like a big, drooping glumbender."

He sighed. "It's nothing."

"Wrong." She shoved him over so that she could make a spot for herself in the little nook where he was sitting.

"I didn't say you could sit down."

"I didn't ask for an invitation."

He heaved a big sigh. "Toph, I kind of just want to—"

"Be alone and glum some more?"

His lips pursed. "I was going to say have some space to myself."

"Well, that's a lie." She wriggled, elbow jabbing into him as she got comfortable. "We all know you hate being alone unless you're having a sulk."

Aang hugged his knees more to his chest so that he wasn't so squished against her. "You're kind of mean sometimes, you know that?"

"I try."

His frown got heavier.

Toph flicked him on the head, right on his arrow tattoo. "C'mon, talk to me. What's put you in a sulk?"

He rubbed the stinging spot with a scowl. "Have you ever thought I just don't want to talk about it?"

"I think you do, and look"—she raised her hands in mock cheer—"I'm all ears. Literally. My eyes don't work."

Aang heaved another big sigh. He turned his head to the wall and avoided looking at her.

"You can talk to me, Aang," Toph said more softly.

The use of his given name made him glance back at her in surprise. She never called him by his name.

"I think I have an idea what this is about anyway," she said with a tiny shrug.

Heat flooded his cheeks. "You do?"

"Katara, right?"

He shifted in agitation. Had he been that obvious?

"You left pretty quickly earlier. About the same time Sunshine and Sweetness started holding hands."

Aang's fingers dug into his knees. "Are they … are they dating?"

"Not that I know of."

He let out a breath.

"But that doesn't really matter, does it? You saw for yourself that something is going on between them."

"Maybe there isn't. If they're not actually together, then maybe … maybe it's nothing. Katara has always been pretty affectionate and—"

"Yeah, let's just stop there. It's painful listening to you trying to give yourself hope."

He hunched more into himself.

Toph patted him on the arm. "I know it sucks, but you'll get over it, Aang. Give it time."

"I can't just get over it."

"Sure you can. Just—"

"I can't! You wouldn't understand."

"I get it. You have a crush on Sweetness, but—"

"It's not a crush! I … I love her."

That was what hurt the most. Zuko had known that. They'd even talked about it at the Eastern Air Temple. Aang didn't understand why this was happening. He felt confused and betrayed and so alone. It was like Zuko and Katara had just been waiting for him to go into that dumb coma so they could go behind his back and get all mushy-eyed with each other. Just thinking about it made his heart ache. He couldn't forget the sight of them holding hands in the mess hall or the way they had looked at each other—the way she had looked at Zuko.

It was like no one else existed. It was like she'd been in her own little world with Zuko, and there was no space for Aang between them.

"I just don't understand," Aang mumbled. "I thought Zuko was my friend. I thought Katara and I had something special, so why ..."

"Maybe you do have something special. Maybe it just isn't what you thought."

"What?"

Toph sighed. "I may be blind, but I'm pretty good at reading people. The way Sweetness gravitates and reacts to Sunshine … she's never done that with you. I know she loves you, Aang. I know she'd do anything for you, but I don't think it's the kind of love that would make her want to shove her tongue in your mouth."

"Toph!" He tugged at his collar, suddenly hot around the ears.

"What? It's what you were hoping for, right?"

His blush darkened. "I never … I just hoped we could maybe …"

"Yeah, yeah. Spare me the awkward denials. I can tell when people lie, remember?"

Aang shifted and hunched his shoulders closer to his neck like a turtle. This was so embarrassing.

Toph stretched her legs out and wiggled her toes. "You wanna know the sucky truth?"

"What?" he grumbled.

"This just isn't about you, Aang. You can have all the feelings you want, but that doesn't mean things will go your way. Sunshine and Sweetness … they're probably going to get together." A snort. "Well, if that big idiot wakes up and sees what's right in front of him. No wonder he's never had a girlfriend before. He's useless."

Aang's mouth drooped even more. "Is this supposed to be comforting me?"

"No. It's the sucky truth, remember?"

He sighed.

"My point is you can't make this about you. Sunshine cares about you a lot and he is your friend. He would never hurt you intentionally, and I think you know that. Honestly, I don't think that big idiot has even realised he has feelings for Katara."

Aang rested his chin on his knees. An unbiased part of him could acknowledge this was true. Zuko was the one who had come to wake him from that horrible place of misty nothingness (not to mention with Katara's help). Zuko had practically ripped his mind and soul apart just to give Katara enough time to heal Aang. That was why this whole thing was so confusing and upsetting. They'd all been through so much together. Zuko and Aang had a bond that linked them spirit to spirit—more than friends, more than family.

But Katara was the girl Aang liked. And he really, really liked her. He wanted to get mad at both of them; he wanted to yell that he had seen her first, that she belonged to him, that she was meant to be with him. Except people didn't really belong to anyone. Deep down, he also knew that Toph was right. Katara had never looked at him the way she did Zuko, and he knew neither of them would actually want to hurt him or go behind his back.

This wasn't a betrayal. It just … was. But that didn't make it any easier.

"I hate this," Aang admitted. "I hate feeling this way. I just wish things could go back to how they were."

Toph squished closer to him, which was about as much of a hug as she was willing to give. "Like I said, it sucks."

"Yeah," he said feelingly. "It really does."

oOo

The hours dragged that day. By the time the moon was rising over the ship, Zuko still hadn't adjusted to keeping his chi suppressed. He often lost concentration, making his inner fire flare right back up, or he just felt so woozy that all he could do was sit with his head in his hands. It was awful. This whole technique was awful, but he was conscious of Yuzo's warning. He had to make this work.

Being a fire healer wasn't a game. People could get hurt. People already had been hurt.

Katara found him later pouring a cup of water for himself. The mess hall was mostly empty, as everyone had started preparing for bed or night duty. Zuko had been on his way to bed as well, but he stayed to chat with her now.

Suddenly, the cup slipped from his hand, hitting the floor with a thunk and spilling water everywhere. His eyes widened and flickered with a faintly luminescent glow. One of the doors of energy inside him was unsealed. His own golden thread seemed to get enveloped by a burning yet cold brand of fire—a tainted thing that latched and clung.

"Zuko, what's wrong?" Katara's hands were on his arms, reaching for his face. "Hey, talk to me."

As fast as it had come, the energy was gone. The door was also sealed as if it had never opened. He let out a breath and looked down to meet her gaze. "That was Azula."

"What? What are you talking about?"

He pulled back from her touch and glanced around the mess hall for Yuzo, his chest tight and his pulse hammering in his throat. Dimly, he was aware of Hakoda and Aang coming over and asking if everything was okay.

"Maybe you should sit down," Hakoda said, placing a hand on Zuko's shoulder. "You're looking a bit pale there, son."

He was distracted into glancing up at Hakoda, confusion wrinkling his brow. Not even his own father had called him son.

Hakoda steered him quite forcefully into sitting at the nearby empty table. "Now, let's see you taking some deep, slow breaths."

Zuko was about to protest—he needed to find Yuzo now—but Hakoda's hand was a firm weight on his shoulder. Hakoda's expression also didn't allow any room for arguing.

"Breathe," Hakoda said, giving his shoulder a slight squeeze. "Go on."

Zuko did as told. It was only as he did that he realised he'd been breathing too shallowly. With each deep inhale and exhale, the tightness in his chest eased and his mind felt clearer.

"See," Hakoda said with a smile. "Isn't that better?"

Zuko lowered his gaze even as his cheeks warmed a little. He didn't know how to interact with this man, especially when they weren't discussing practical things like the eclipse plans or getting to the island.

Katara sat next to Zuko on the bench. "What happened back there? You said something about Azula."

"I … you know how I bonded with her when I healed her?

"Yeah."

"Well, I can always feel that link, but this time it was different. It was …"

She touched his knee when he remained silent. "What?"

His gaze flickered to Aang, who lingered a bit behind Hakoda and looked small and subdued. "It was like what happened with you, Aang."

Aang's brow furrowed. "What do you mean?"

"Twice you've manipulated our bond on your own, pushing beyond the seal that keeps our energy from linking any further. Whatever just happened, whatever Azula did, it was like that. It was like she'd somehow managed to take control of the bond and …"

He tensed, remembering how it had felt to have her chi envelop his own. Clawing. Desperate. It was like she had been scrabbling at him with her fingernails, a hungry mass that had wanted to burrow deep and become a part of him. It had been repulsive yet, oddly, also slivered him with pity. Her energy didn't feel right. There was so much raw power—so much—but it was also like brushing against sickness, an ugly thing that had been eating away at itself for years.

"Zuko?" Katara rubbed his knee in slow, soothing circles. She must have noticed the stiffness that hunched his shoulders.

He exhaled. "I don't know what she was trying to do. I didn't even think she'd be able to do something like this."

"Why not?" Aang said. "I did. You said it yourself what she did felt the same."

"Yeah, but you're the Avatar; you've got all that crazy spiritual power. Besides, the only times you've manipulated the bond on your own was when I was half-dying or asleep."

Hakoda frowned. "In other words, your guard was lowered."

Zuko nodded.

There was a pause as they all digested this information.

"I need to talk to Yuzo," Zuko said, standing swiftly. Too swiftly. Stars burst before his gaze and he wobbled.

Katara steadied him from behind. "Maybe you should stay put for now." She tugged him to sit back down on the bench with her, hands lingering on his arms. "You still look pretty pale."

"But I—"

"I'll bring Yuzo here," Aang offered. "I'll go look for him now."

He dashed off before anyone could respond.

Katara smiled and said she'd get Zuko a fresh cup of water. Soon, it was only Hakoda and Zuko. He kept his gaze lowered and scratched at a non-existent itch on his hand. Prickles of awkwardness crept all over him. This was even worse than that time he'd run into King Kuei in the garden.

"Still feeling dizzy?" Hakoda asked.

Zuko's shoulders crept higher towards his ears. "I'm fine."

Hakoda raised his eyebrows. Maybe he had noticed the mulish defensiveness in Zuko's tone, but Zuko couldn't help it. Azula breaking the seal, the dizziness, being fussed over and forced to sit down—all of it made him feel so weak. It opened old wounds of insecurity. Hakoda was probably judging him right now for getting so shaken.

"It must be tough."

Zuko's gaze flickered up in question.

"I'm not a bender, so I can't understand what it must be like to have abilities you don't fully understand or control. I just know I don't envy you. It sounds like these energy bonds are not a simple thing."

"They're not …"

Hakoda sat next to him. "Can I ask you something, Zuko?"

A nod.

"Do you have an energy bond with my children?"

Zuko let out a small breath. That was a question loaded with interpretations.

"I'm not saying I don't trust you," Hakoda was quick to assure him. "From what I've seen and heard, I don't believe you would hurt Sokka or Katara, but I just want to know. Are they bonded to you like Aang is?"

"No. I've never healed them, so …" He trailed off, remembering how Katara had asked him to let her help with bringing Aang back.

"What?" Hakoda prompted.

Zuko frowned and focussed on his inner fire, feeling for the different links he had made. There was Aang, always the strongest. Then there was Uncle, Changpu, Biyu, Azula and …

His heart sank. Katara. Her energy's signature was there. He hadn't noticed the connection because her bond with him was so much subtler than the others. It felt less like a door with a seal and more like a hand he could hold if he wanted. Perhaps it was because he hadn't given up any energy for her.

"I … have a bond with Katara," he admitted.

Hakoda closed his eyes.

She arrived a second later with a fresh cup of water and sat down in her previous spot, handing the cup to Zuko. "Feeling better now?"

He grunted in reply, conscious of the way Hakoda was watching them both. It made him have an odd urge to put more space between them on the bench, as if he was somehow sitting too close to her now even though it was no different from how they'd been sitting together before.

Fortunately, Yuzo soon turned up, though there was no sight of Aang. Once the situation was explained, Yuzo frowned and said he wasn't sure what Azula had been trying to do. He couldn't profess to be an expert on bonds.

"I've only ever bonded with Atsuo and my mother," Yuzo explained, "and they never did anything like that to me. But what I do know is bonds link our energy, our very spirits. They can be used in a lot of ways if you're determined enough."

"Determined, huh?" Zuko murmured.

Azula certainly had a lot of determination. It was a family trait.

"You should be careful," Yuzo warned. "If your sister is no friend of yours, I can't imagine she's up to anything good."

"Is it possible to sever a bond?" Katara asked.

"No. Once a bond has been made, a fire healer will stay connected to that person until one of them dies."

Hakoda frowned. "What about the other people connected to Zuko? Are they in any danger?"

Zuko tensed, knowing exactly why that question had been asked.

"I don't know," Yuzo admitted. "In the tribe, fire healers get trained to heal and learn control, but we're not allowed to form bonds with multiple people. That was the Unnamed One's thing. It's considered too dangerous."

"I see …" Hakoda glanced from Zuko to Katara. "Well, that's comforting."

Zuko stared at his palms, the same that had guided his energy into bonding with so many people. What had Azula been trying to do to him? He wished he knew.

"Just be careful," Yuzo said, shaking Zuko from his thoughts. "If she tries again, which I'm guessing she will, make sure you block her out."

"How is he supposed to do that?" Katara asked.

"Willpower." Yuzo held Zuko's gaze, his own eyes hard and challenging. "It all comes down to willpower."

Ack to this chapter. So much love stuff going on. (I'm just not a fan of love drama and cringe every time I have to write it. Even worse when more than one character likes the same person. *shudder*)

Anyway, love stuff aside, I had to giggle a little to myself while writing this because I realised the whole masking energy thing is a bit like ki suppressing from Dragon Ball Z. But it works, so meh. Of course, I don't like things to be too simple/easy, so Zuko has to learn to keep his inner fire low and adjust to the change in energy balance.