The heat felt like a physical wave rolling over her, and Katara had to struggle not to faint. When they'd said neutralizing, as it turned out, they'd meant neutralizing.

Of course, it wasn't exactly a comfortable thought that she was being neutralized as well.

"Do you need to sit down?" The guard who'd escorted her in was looking at her with concern. "Most people who aren't used to it need a few minutes to acclimate."

With a grateful nod, Katara took the indicated chair, taking a few minutes to close her eyes and breathe, steadily, in through her nose and out through her mouth. The air smelled of sulfur. After a few minutes, she felt safe to push herself to her feet, though her legs still wobbled slightly underneath her.

"No water past this point." The guard held out a hand.

Katara could hardly have felt more vulnerable if they'd told her to strip. Nevertheless, she unstrapped her waterskin and handed it over, then held her arms to the side while a female guard ran quick hands over her torso and legs, checking for hidden flasks or contraband. They could not afford to take any chances.

Straightening up, the guard who'd frisked her nodded, and the others gestured her to a steel door set in the side of the mountain. As the door was cranked open in a scream of gears, however, Katara took an involuntary step back.

She was looking at a cage.

The door on her side was open, true, but Katara could see the lock for which she had no key, and the rest of it was a cramped cube of solid bars with a mesh floor, barely big enough for two people, swinging precariously over the caldera by a thin steel cable.

Her fear must have been evident on her face. "The bars are for your own protection," the guard who'd escorted her in explained, stepping up. "It would be hard to explain to people's families if someone lost balance and fell.

"If you need to hold onto something," he continued, "there are handholds here and here." He pointed out several places where the bars had been wrapped with cloth. "The bare metal can get rather hot down there, hot enough to burn, so be careful where you're putting your hands. Once you're ready to come up," he indicated a slender length of rope that hung slack from the ceiling of the cage, "pull on this. If it's an emergency—you start feeling faint, or the prisoner is doing something dangerous—pull twice, and we'll get you back up as quickly as possible, though it'll be a somewhat rougher ride. We'll bring you back up again after fifteen minutes whether we've heard from you or not. If you want to see how much time you have left, flip this," he pointed out an hourglass set into the side of the cage, "once you get to the bottom." Katara nodded to show that she'd understood.

With one last deep, shaky breath, she stepped into the cage and wrapped her fingers around the indicated handholds. The door clanged shut behind her. Then, a brief jolt, and the cage was moving, swinging out over an immense lake of boiling lava, waves of heat rising up and threatening to overwhelm her, the intensity increasing with each passing second. Katara should be sweating buckets right now, she knew, but any hint of moisture was seared away the second it reached the surface of her skin. She gripped the bars harder, leaned her forehead against her hands, and focused on breathing.

"Do you want me to come with you?" Sokka had asked, eyes full of concern, when she'd told him what it was she'd intended to do. He was remembering what had happened the last time she'd run off for a confrontation; she could see it in his eyes.

Katara, however, had answered him with a shake of the head. "No," she'd said, softly but with conviction. "Thanks for the offer, but this is something I have to do on my own."

The cage ground to a halt, swinging from side to side with a motion that combined with the heat to make her feel queasy and lightheaded. She had reached the bottom.

When she reached out to flip the hourglass, her hand was shaking. Her eyes, however, were not on the hourglass: Katara was looking past it, past it and into the bars of the other cage that was now directly across from her, her eyes locked on its occupant.

"Hello, Hama," she heard herself saying, as if instead of a prison they were back at the inn and about to sit down to tea.

Slowly, the other woman looked up. Curtains of white hair hung down around her head, hiding her eyes. Her mouth, though… her mouth was spread wide, in that same insane grin she'd worn when she'd tortured Katara, when she'd made puppets of Sokka and Aang to force her into learning the horrible technique against her will.

Katara hadn't expected her to be broken. Half a lifetime in a Fire Nation prison hadn't done it; a mere year in here wasn't likely to either. Still, it was unnerving that Hama could still look at her not with anger or resignation, but with the self-satisfaction of having accomplished her life's goal: she'd let another bloodbender out into the world.

"Hello, Katara." That self-satisfied smile never left her face. "I've been expecting you."

Almost without her noticing, her fingers tightened around the bars hard enough for her to feel the heat of the metal even through the cloth before she hastily forced them open and clenched her fists at her sides instead. She'd come here for closure. Instead, Hama was twisting the encounter to give herself the upper hand—just as she always had.

Katara opened her mouth—angry, humiliated—but no retort would come out. Instead, she could only glare across the bars, and once again Hama was the one to speak.

"So." Her voice was like ice in summer, cold and slick. "Whom did you use it on?"

There was no need for Katara to ask what she meant. "Fire Lord Zuko." Her voice came out in a whisper.

Hama's grin widened. "Better," she cackled. "Far better than even I would have dreamed. You surpassed even my wildest expectations, Katara."

"He'd been poisoned." She wanted her voice to be defiant, but instead it only came out weak and pleading, as if she were trying to defend herself after being caught in a terrible crime. "His body was shutting down. He'd stopped breathing. His heart had stopped beating. And I… I made it beat again."

Something in her had been hoping that that information—that she'd taken Hama's intended vengeance and instead used it to save a life—would wipe the glee off the other woman's face, would make her angry or disappointed or would cause her to crumple in defeat. Instead, she let out yet another cackle.

"What's so funny?" Katara demanded.

"It's perfect." Hama's grin was now so wide Katara was surprised it hadn't physically split her face.

"How is that perfect?" She was beginning to panic, her heart pounding against her ribcage and bile welling in her throat. Her head spun. "Did you even hear what I said, Hama? I used your technique to save his life."

"You never seriously believed I actually wanted you to kill anyone, did you?"

This time, no retort would come. She was swaying on her feet, and had to grip the bars just to keep herself upright.

"Death would have been a welcome release, after what the Fire Nation put our tribe through." Now she was angry, her voice coming out in a hiss and her eyes narrowed to slits. "They should have killed us when they caught us. It would have been more merciful than being starved, chained, dehydrated and brutally beaten day after day for years on end, with no hope of release. Do you think that death would be sufficient to repay such a crime?" No: she already knew the answer. They'd found it, when they'd found all those people screaming under the mountain…

"The people of the Fire Nation do not need to die. They need to suffer, as our people have suffered at their hands. And you—you have continued my work, whether you wanted to or not! Tell me, Katara." She was getting up now, moving to stand at the near end of her cage, and though they were too far apart to touch even if they were to both lean against the bars and reach out their hands, it was still too close. "Did he thank you, when you were finished? Or was he too preoccupied with writhing in agony? No, he is going to remember that moment, remember your power over him, for the rest of his life—and thanks to you, it is going to be a very long life indeed."

A hand clenched around her forearm, hard enough to leave bruises…

Tears spilling from beneath his good eyelid as she worked her hand… Zuko never cried, especially not for pain…

A single cracked syllable, forced in a whisper from between parched lips…

"…he did thank me."

He'd barely been able to talk—he'd barely been able to breathe. He'd been grasping Iroh's hand as if clinging to a lifeline. Even so, he'd undertaken the immense effort to force out the word, because as painful as it had been he knew what it was she'd done for him, that she wouldn't have hurt him if she'd had any other choice.

…another choice…

"Hama," she continued, cutting the other woman off as she opened her mouth once more. "I'm truly sorry for what's been done to you, and to the rest of our people." There was plenty of sand still left in the hourglass, but Katara knew now that she would not need it—she had finally found the words she had needed to say. "But there's no longer anything I can do to help you. Help is something you have to want, and you've already chosen your path." Steadying her feet beneath her, she unclenched one of her hands from the bars, and reached upward. "Goodbye."

When her fingers closed around the rope, she only tugged once. Even though the heat was quickly overwhelming her and darkness was starting to gather at the edges of her vision, she did not want Hama to think she was running. There was simply nothing more she had to say.

Furious screams echoed from behind her as Katara closed her eyes and sagged against the bars, but she paid them no mind. Nothing Hama could say to her could hurt her anymore.

Hama had taught her bloodbending with the intention that she inflict pain, and in that, at least, she had succeeded. It had been necessary—Katara knew that. She'd known all along that sometimes, in order to help people heal, it was necessary to hurt them first: setting a broken bone, stitching a wound, cauterization to stop uncontrollable bleeding… Though she had never flinched away from doing what she had to, neither did she revel in it. She did not like to see people hurt.

Sometimes, though, there was a better way. Since she had learned water healing, Katara had not had to stitch a single suture, and it had made things better for everyone involved. Surely—surely—she could figure out a way to get past this too. Now, the only thing left was to hope that the idea taking seed in her mind actually worked.

There was no longer anything more that Katara could do for Hama—but she could still help Zuko.

"Are you comfortable?"

"Does it matter?"

"I think that it does." He looked at her incredulously, and she let out a slight sigh. "Humor me."

"More or less, I guess." His shoulders moved upward in the slightest of shrugs. "Getting tired of this bed, to be honest."

"Well, hopefully you won't have to be in it for much longer." The curtains were open, allowing the white light of the full Moon to spill into the room. "So what do you say?" She tried to smile, but her mouth couldn't quite seem to find the right shape. "A few minutes of bloodbending in exchange for a long, full life?"

"Katara, it feels like you're trying to rip my heart out." His voice came out in a whisper.

"I'm not. I know that it feels that way, but I'm not, and I won't." Closing her eyes, she took a moment to gather all feelings of passive-aggressive bitterness, and then to let them go. "You do trust me when I say that, right? Please," she continued when Zuko opened his mouth. "I need your honest answer. This is important."

To her surprise, he gave a slight chuckle, but when his free hand moved to rest over a star-shaped mark on his midsection, Katara understood. "I think you already know the answer to that."

"Good." A smile—a real one this time—tugged at the corners of her mouth. "Are you ready?"

"No." Though his pulse jolted under her fingers when she asked the question, his voice remained admirably steady. "But I'm never going to be ready, so just go ahead and do it."

"Do you want anyone in here with you? Sokka? Your uncle?" In answer, he only squeezed his eyes closed and shook his head, so Katara set his arm gently back down at his side and stood.

She'd already folded the covers down to his waist and draped his robe over the back of a nearby chair so she could listen to his heart, and now he lay bare-chested before her, his scars standing out lividly against his pale skin. Of course, she'd seen Zuko without his shirt on before this, on many different occasions—but this was the first time Katara had seen him look so naked.

"I'm going to try something a little bit different this time, and I'm going to try to make it not hurt as much. And I know this is going to sound really stupid," she said. "But try to relax."

"Relax. Right." With a visible effort he unclenched his fingers from the sheets and let his hands rest limply at his sides, taking in a few deep breaths with his eyes closed. Tension still ran through his body, but Katara had to acknowledge that he was genuinely trying, which was better than they'd been doing a week ago. Reaching out, she rested a hand against his chest, her fingertips brushing his skin with a feather-light touch.

She could feel his heartbeat.

The damage was still there, outlined clearly in Zuko's blood. This time, however, Katara knew that she could fix it. All she needed was to have faith in herself—and in him.

"A good healer works with the body, if at all possible—not against it." That had been Yugoda's first lesson to her, when she'd attended that class she hadn't wanted to go to because Pakku hadn't thought she was good enough to bend with the boys. At the time, anything she might have learned had been overshadowed with resentment, the deep bitterness that she was only allowed to do something "lesser" for no better reason than the way she was born. Though her conviction to learn how to fight had not changed since that time, her views on healing had, and now Katara recalled that lesson as she counted the beats of Zuko's heart.

A contraction—she pushed. The muscle relaxed—she pulled. Bit by bit, Katara nudged the damaged tissues back into alignment, trying to work with the rhythm of his heart, the flow of his blood. Everything was clear to her. It was almost as if she held Zuko's beating heart in the palm of her hand.

"Hey, Katara?" At least he spoke quietly; working with the body or not, she was still all too aware of the power she held, and did not like to think what she was capable of doing by accident if startled into an involuntary twitch. "Are you planning to start any time soon? I've had about as much suspense as I can stand."

"Actually, I already started."

"Huh? But I don't feel anything…" With a slight shift, he reached up as if to touch his chest, but Katara grabbed his hand with her free one and gently pushed it away.

"Don't," she warned him. "I'm still working. I did tell you I'd be trying something a bit different."

"A bit different? But…"

"I didn't know how well this would work, and I didn't want to get your hopes up if it didn't. Now hush. I need to concentrate."

With a nod, he lay back, and this time the tension truly eased from his muscles as he let out a breath and relaxed at last. Once she saw that he truly trusted her, Katara began to work in earnest, beginning the major repairs that would keep Zuko's heart healthy and strong, hopefully well into his old age.

He was going to get past this—and, just as importantly, she was as well.

A/N: A little inside joke of mine is that I like to write Zuko and Katara in every possible type of relationship imaginable—except for romance. This was the story where I explored the doctor-patient aspect of their relationship. The title of the story was specifically taken from the Hippocratic Oath. Specifically, "Practice two things in your dealings with disease: either help or do not harm the patient." That sort of dynamic was what I was trying to get across here.

For the record, yes, I think that it's in character for Katara to regret not having put more effort into learning how to heal. I do not think that it's in character for her to regret having learned how to fight—think about the lives she's saved specifically thanks to her skills in combat, and that argument gets thrown on its head.