It wasn’t something she noticed right away.

When she did notice, when she realized what it was, it made her sick to be in her own skin.

She hated herself for it, for what Hama had forced her to do with her bending. She hated how achingly powerful it made her feel, to be able to have the pulse of the older woman beneath her fingertips without even being within arm’s reach. To be able to feel the skittish rattling of Aang and Sokka’s hearts ricocheting in the back of her throat, even if she didn’t reach out for them with her bending.

It’d been a creeping sensation sliding beneath her skin ever since encountering the old waterbender, but it wasn’t until they were on the way the Western Air Temple that the full weight of understanding sank into her like a heavy stone to the bottom of the ocean.

Katara could still sense the pulse of not only Aang and Sokka, both of whom she’d felt under Hama’s control, but the blood of everyone around her. It shifted and thrummed at a low, low level, like undercurrents beneath the stronger tide. The same way she could feel the siren call of the dark depths of the ocean, the muted beats of pulses not her own called to her, tried to lure her down to them.

During the day she shoved as much of her friends’ heartbeats as she could aside, keeping the disquieting desire to sift through them one by one at bay. She had plenty of distractions to busy herself with—preparing all the meals for the group, conversations she threw herself into, practicing bending forms as they walked. But, in the quiet dark of each night, when she was only half awake and curled up on her side, there wasn’t enough to keep her curiosity from wandering back to the chorus of pulses surrounding her.

Three days before they reached the Western Air Temple, Katara finally gave up on sleep, the last iron of her resolve rusting away. With everyone asleep around her on the grass, she drew in a breath and let her water sense expand.

She could feel each pulse at the very tips of her fingers. Sokka, she realized, was the cadence in her ring finger; his was a familiar pulse, one she’d known for a very long time. Lingering in the floating space before true sleep, Katara listened to her brother’s heart, steady in the night. It grew and filled the edges around her so clearly, she could convince herself they were back home, back in the frozen south with skins and furs and fleeces piled all around them and her head was pillowed near his back.

This opened a new possibility for her. As well as she knew Sokka, she wondered if she would be able to always sense him now in a way more definitive than just a sister’s intuition. Would she be able to pluck his heartbeat from among any others with the same surety with which their mother had plucked each tautirut string? Would it always be there for her to listen to if he was near? Being able to have his presence always there so long as a heartbeat should have been a comfort to her, if it didn’t make her wonder just how close to the surface thisperversion of her bending had been her whole life.

In the daylight, she found herself watching him, wondering, a slow twist of disgust twining around her stomach. Did she really remember Sokka’s heartbeat and reassuring heat from the years in their family’s igloo, or was she always destined to bloodbend? Was it always in her nature, hidden in the depths, simply waiting to be called up to the surface?

Disgust roiled inside her to think that such an awful power was lurking in her waterbending, something she loved so dearly. She retreated a distance from the others while they were distracted by lunch and promptly retched up the rice and vegetables she’d eaten.

After her stomach finally stopped lurching at the notion that she could concisely identify her brother’s heartbeat five people away, Katara took in a deep, shaky breath, searching for a calm center within her mind around which to orient herself. She had to look at this rationally, had to parcel this into manageable pieces. Perhaps she could find a way to stop sensing everyone around her, learn to control it, learn to silence the transfixing rhythm of hearts beneath her own, to quell the tug lingering in her fingers to reach out and dip into the currents in each of her friends and companions.

A small, derisive voice in the back of her head that she did not like whispered, It will be as easy as stopping you from waterbending.

Still, she had to believe there was a way to control it, so that whenever she felt a rush of blood not her own it wouldn’t send her into waves of nausea from the knowledge.

The days of their trek to the temple passed, days spent intent on her own breath, on narrowing her focus to that of her own heartbeat to try and drown out all the others. Eventually, she was able to distance her awareness enough to feel somewhat comfortable again. In that space she—against her better judgement—could not help but undertake a cautious, tentative examination. Now that the initial, immediate revulsion had passed over her, Katara felt something akin to curiosity that she wasn’t quite ready to admit as such.

She spent careful time during each of the next three days dedicated to the very controlled and slow exploration of reaching out with her bending to simply sense what she could. There was water everywhere: the moisture in the grass, dew in the mornings that evaporated as the sun rose; the winding sluice of a stream to the norther, far beyond the sight or hearing of anyone else but her; the beads of sweat that had gathered at the backs of all their necks and curves of their spines as they walked beneath the sun.

All these things she knew the very first afternoon they’d spent in the temple, without even trying. She went further.

The soil beneath them held water—an amount comparable to a heavy fog, but not as easily drawn out. Still, she knew that she could pull it up to her fingers if she wanted to. If she needed to. Even the stones that lay scattered about the grassland they walked through held beads of moisture trapped in cracks or more porous spots. The water there would be even more difficult to reach, but she still could. Her fingers itched at the thought of stretching her abilities again, to draw water from the very stone itself.

Despite the distaste on her tongue at the thought of the one who taught her to look for water in everything, being able to know these things now made her feel powerful, made her feel good.

It was what lay beyond simply knowing where to find water in the least likely of placed, what power she would find in the blood currents of others, that frightened her.

It took her two more days, but Katara, sitting still and straight in the middle of the night during her watch, bit her lip and finally steeled herself to sink down to the litany of pulses waiting for her to know them.

At first, it was overwhelming, allowing herself to wade into so many different heartbeats pulling and pushing in different bodies. They were all oceans unto themselves, and Katara could not tell them apart. She sucked in a breath, but then forced herself to release it and focus again. Sokka—she knew him, knew him for all her life, she could find him anywhere—and so she stilled herself and parsed through all the rhythms like fingers threading through drifting silk strands until she found him. Her ring finger tingled. Even through her trepidation, it emboldened her.

She drew in and then exhaled another steadying breath. Her eyes fall shut as she submitted to identifying the living currents around her.

Toph she felt in her littlest finger. The even, strong pulse of the earthbender’s heart ran a line along the outside of her finger, down the length of her hand until she lost it somewhere among her wristbones. It was slower than the others she could feel, but had more power with every beat, and if she let it she could feel it vibrate every bone in her hand. In a strange and almost disconcerting way, it was almost as much a comfort as Sokka’s.

Katara wondered, suddenly, if this was similar to the way that Toph navigated the world, through the overt and subtle vibrations everyone made as they moved and lived on the earth itself. Her eyes flew open as she considered the possibilities that started to trickle into her mind. What if this could be the equivalent with her waterbending? She wouldn’t be limited by what sort of material a person was standing on—Katara bet that with enough practice, she’d be able to determine the distance and state of a person if she needed to.

Even as practical, even useful applications of this… extension of her waterbending took form in her reasoning, the revulsion returned. How could she be doing this? How could she be seriously considering using the blood in someone else, even if it were for what could be argued as a good cause? Blood was one of the most intimate elements a person could posses, it wasn’t a toy for her to tap into whenever it suited her.

She unfolded her legs hurriedly and ran to a spot far enough away from the others and retched onto the ground.

This was a bad idea.

She should stop.

But the moon wasn’t near enough to full for her to worry she’d accidentally use the power she now possessed, and what harm was there if she couldn’t really do anything? In the end, her curiosity proved stronger than her fear. She felt quiet patterns tapped out between all her friends, and she couldn’t help herself.

She’d only use it to help them, to find them, to heal them, she resolved. She’d never, ever use it to control someone again.

Relenting with a quiet escape of breath, she sat on the pallet laid out on the stone slab of some ancient monk’s bed she now used, Katara then yielded to the deep undercurrents and let them take her where they will this time.

Haru had a similar pulse to Toph’s—just as steady, but not quite as slow, not quite as strong. Teo’s pulse was lighter, with more pulling than pushing, as if his very blood was trying to help him get off the ground. The Duke’s was more rapid, but he was much younger than everyone, and the most energetic of the three, even deep in sleep as they all were.

She found Aang in her longest finger. It was a strange, almost rolling pulse that started at her knuckle and ended at her fingertip, and she wondered at the distance it traveled in a single beat. It felt like the length of millennia, of generations. The length of lifetimes. Katara could feel spacious, carefree resonance echoing with every push outward that his heart made. She could feel all the things that made him a nomad, an airbender down to the very blood in his veins, but she could also feel the solemnity that drew heavily back to his heart. It was weight that he bore as the Avatar for centuries, and would continue to bear for centuries after she was long dead.

Katara lingered on the cadence of Aang’s pulse the longest, flowing with it in her mind but not interfering, not reaching out—not that she could, as it wasn’t the full moon yet. She allowed herself to simply drift along, letting the push and pull of his heartbeat dictate her accompaniment. It was hypnotizing, inducing a lulling trance that seemed to slowly draw her further in and further down into the depths beneath the weight he carried inside him. She didn’t realize she was completely engulfed until her chest constricted sharply, her heart pounding erratically and giving her the sensation of drowning—something she had never feared since she began waterbending in earnest.

With a sharp gasp, she snapped back from Aang’s pulse and grasped at the strange, uneven hammering in her chest. It was difficult to breathe for several terrifying moments before she forced air deep into her lungs to prove to her body that she wasn’t drowning. Her heart slowly calmed to its normal rhythm, and the pain in her chest faded.

Carefully drawing in long, steadying breaths, Katara tried to determine what had happened. One moment she was sinking into nearly ten thousand years of lives and the next she felt her own heart might explode. Lost. She must have gotten lost in his undercurrent, strong and ancient as it was. That alone didn’t explain the constricting pain she felt clawing up through her heart out to her lungs. She found no answer by the time she woke Sokka for his turn at the watch and laid down against Appa’s side. Weariness spread from her heart outward, overtaking her.

She slept in late the next morning without meaning to. The others must have decided to let her be for once; normally she would have gotten up in haste and apologized in a flurry, rushing over to the cooking fire to make sure everyone got fed. This time she stayed cushioned on Appa’s fur, thankful that breakfast was being made on the opposite side of where she lay.  Eventually, she would get up and join them, but for now she closed her eyes against the light of the morning and drew in a rattling breath. She felt an odd ache in her chest—it wasn’t the ache of muscles or bone, but something deeper, like her heart had strained too much for too long—and she wanted nothing more than to rest for a while longer.

It was then she remembered losing herself in the pull of Aang’s pulse. A furrow creased across her forehead and she worried the plane of her sternum with her fingers. She hadn’t felt tired at all, but after pain had gripped her chest, it seemed as if all the energy was drained from her body. Katara frowned, trying to recall as many details as she could about it. It was difficult to pull single moments of memory out of the trance-like state she’d been lulled into.

As if summoning it, she felt the rhythm of his heart again. Almost immediately upon feeling his cadence again, Katara was nearly dragged back into it, but she was prepared this time, and held herself firm against the tug of it.

It was then she felt it—the stuttering of her own heart for a few beats, trying in vain to match his. That’s what had caused her pain last night, she realized. His pulse was such a force with so many lifetimes behind it, that her heart had responded and tried to change her own natural rhythm to match his. A relieved sigh left her, and she felt muscles she hadn’t realized were tense relax. No wonder it had been so uncomfortable—his heartbeat was faster than hers, and it went against every rhythm in her body, immediately rejecting the rhythm and snapping her out of her trance.

Biting her lip, Katara ventured to sink just a bit into the pull of his heart and sway of his blood as he moved around the campsite, getting ready for another day of walking. She wanted to see if she could keep her feet beneath her, not get swept away as she did last night.

It worked.

She drew back, holding his and everyone else’s pulses away—something she was already better at doing, now that she could parse through each pulse individually. Perhaps it wasn’t so bad after all, she ventured to admit to herself. She’d satisfied her curiosity, and eventually she might be able to develop benign uses for bloodbending—uses that didn’t include forcing someone else to her will.

She finally got up and stretched as much weariness out of her bones as she could, then went over to join the others. A quick bowl of congee satisfied her for breakfast, and then she helped clean up the campsite so they could start their trek again.

They walked for a good portion of the morning and afternoon, sighing complaints and worries to one another. Halfway through the afternoon, Toph stopped suddenly, planting her feet and lifting her chin. “Hey, we’re here! I can feel it!”

Katara glanced around. “Uhh… I think your feet need their eyes checked,” she told Toph.

“No,” Aang interjected, “she’s right. We’re here!”

“Wow…” Toph breathed. “It’s amazing!”

Words of disbelief and confusion flitted between them all, but then they clambered up on Appa again, and he took them down below the cliffside.

Toph was right—it really was amazing. Katara had no idea that buildings could even be built on the underside of a cliff like that. Every archway, terrace, and rooftop was as graceful and meticulous as the Southern Air Temple’s had been. It was also just as empty and echoing. Katara saw a brief shadow pass over Aang’s face before it faded. It was difficult for him not to hope they would find someone still hiding in one of the temples, she knew. The flashes of his grief plucked at her heartstrings every time. She resisted the urge to draw him into her arms and console him.

Instead, they landed and disembarked out of Appa’s saddle and Aang excitedly talked about the things he knew about this place. Watching him as she and Sokka gathered their traveling packs out of the saddle, Katara wondered if he’d been here a hundred years ago. Had he visited all the temples during his native time, or was he just taught about them? She’d never asked him before, and now found herself curious.

Teo, Haru, and the Duke soaked up Aang’s enthusiasm like sea sponges, chattering to each other about what they wanted to explore first. Their plans quickly devolved into a racing challenge. Katara saw exactly where this was going—and who would be the first to follow after the trio.

She stopped Aang’s exuberant exit short with his own staff, preventing him from following the other bows on their exploration of the temple. Instead, she led him back to a fallen column where Sokka and Toph perched upon the broken stones, somber. The mood leeched out of Aang as soon as he sat with them all. The anxiety coming from both Aang and her brother was nearly palpable in the air. Not surprising in the least, but it put them all on edge, feeding off one another and the narrowing window they had to bring any kind of plan to fruition.

Well. No time but the present; better to rip a leech off right away than let it linger.

A few days before, Aang had avoided all attempts she and Sokka had made to talk to him about a plan, about finding him a firebending teacher so that he could face the Fire Lord—nevermind that their options were severely limited. It had to be done, so they would find a way to do it. They had no other choice.

So she brought up the need for a firebending teacher, again. Aang, predictably, argued with her. Again. She argued back. It was a now-familiar push and pull to their dynamic, and as much as she cared for and believed in Aang, he frustrated her to no end sometimes.

She was about to lean into her argument and not allow him to avoid the situation any longer when he verbally pivoted around anything else she might have said as surely as he turned his airbending circles in zhuǎndòng yuánquān, and snapped open his glider.

“Oh well,” he declared in a definitive rush of breath, “guess we can’t come up with anybody. Why don’t we just take a nice tour around the temple?” He jogged to the edge of the temple and glided off into the air, Momo trailing behind him.

Katara let out a sound of exasperation, a low noise that vibrated through her throat. It was times like this that she wished he would have been older when he vanished from the world. She wished that he was someone who’d embraced more of the gravity of being the Avatar instead of being just a young boy who hadn’t been given enough time to grow up and simply play.

She released a heavy breath, laden with the irritation that she had to start growing up four years younger than he was now. As much as she hated it in a small, locked away corner of herself, she’d never shirked the duties she knew she had to do. In that same corner, she stuffed the spikes of resentment of having to act his mother at times, and climbed up on Appa. Both Sokka and Toph followed her suit—even Toph understood the importance of finding a solution and she was the same age as him—and took off after Aang.

“Aang, can we talk about you learning firebending now?” she called after him, the sharpness of her tone parting the wind before them like a guandao blade.

He shouted back about the wind being too loud—she knew it wasn’t and that he’d heard her just fine—and then spiraled into a great arcing loop in front of them with his glider. Katara tightened her jaw.

Next to her, Sokka called out next. “Aang, I think we should be making some plans about our future!”

This seemed to finally get through to him, and they followed his curve downward and back to the temple proper. Was he more open to talking because firebending wasn’t mentioned? Or was it because she wasn’t the one making the suggestion? As soon as that question formed in her, a hot twinge of annoyance twisted at the bottom of her lungs before she could stop it.

“Okay,” Aang shouted as he descended. “We can do that while I show you the giant pai sho table!” He landed and kept talking, excited and determined to avoid. “Oh, you’re gonna love the all-day echo chamber!”

They landed behind him and slid down Appa’s sides. All at once, Katara felt an abrupt intensity prickle beneath her fingertips, distracting her from what Aang was saying. Next to her, Toph straightened a little, motion back past the great girth of Appa.

“I think that will have to wait,” the earthbender said.

A new pulse came sweeping in like the tide against the shore of Katara’s heartbeat, slipping down into her veins with a curious warmth. It almost gave her a sense of disorientation, feeling a strange ripple that began deep in the well of her ribcage and ran out and down through her limbs. It made her entire body fill warm.

Zuko—it was Zuko.

The last time she’d seen Zuko was a thousand leagues from where they now stood, and it felt like a lifetime ago. Even though she’d never fathomed of bloodbending the last time they’d encountered him, she instantly knew it was him before she turned and he came into her view.

He was a sudden bright heat in her thumb, a sharp, concentrated pulse the way a healing wound felt. Somehow, his pulse felt hot, like she might warm her hands from it by the sheer virtue of his nature. His heart’s rhythm was steady, if a little fast, and the thick rush of blood through his veins made her almost feel drunk, as if from overly rich lychee wine.

Katara had to suck in a quick rush of air to remember herself and draw back from the lure of wading further in to submerge herself in this new pulse. Her hands curled in on themselves, and she clenched her jaw so she could separate herself from the pulse in her thumb, giving her room to breathe. She shoved anger in the space she created as he supplicated himself before them.

She had to remind herself that she’d trusted him before, had started opening up to him—and she thought he had started to, along with her. With the way his voice had softened at his apology, at the mention of the mother he’d lost as well, she’d thought perhaps there was something in him that hurt as much as she did. But that’d been a lie that even now still stung her as if he’d slapped her. So it felt good, it felt sharp and satisfying in the cracks of hurt in her he’d caused beneath Ba Sing Se, to drench him with water and shout at him to leave.

The way his pulse stuttered at that, she knew he’d be back. Katara could feel the determination flooding through him, despite her outburst. She clenched her hands to try and stop the new throbbing in the pad of her thumb.

He didn’t deserve a place in her hands like everyone else, like all the others she was close to. Katara wasn’t close to Zuko, and she didn’t want to be. Not after how quickly and easily she’d started down that path before.

When they were attacked and he came back, trying his best to help them—when, in the aftermath, everyone else grudgingly accepted him, Katara didn’t want to agree. She didn’t want him in their group, tentatively or not. She didn’t want to feel the strength of his pulse in her thumb.

But. She knew they were out of choices to find Aang a firebending teacher. She had no choice but to defer.

Katara waited until she was sure Sokka and Aang were well out of earshot before entering the open doorway of his room, her own blood roaring in her ears.

The young man who’d chased them all around the world who was somehow, somehow now precariously within the folds of their group was smiling as he gently fingered the frame of a picture. Such a soft expression caught her unawares; it caught and tightened something deep in her stomach.

He seemed to sense her and turned, and she felt the slightest hiccup in his heartbeat, saw the slightest smile form on his mouth before it quickly faded.

Good, she thought. Let him worry about me. He should.

“You might have everyone else here buying your… transformation,” she leveled at him like a kunai blade, “but you and I both know you’ve struggled with doing the right thing in the past.”

The cloth of her tunic scraped harshly against the stone doorframe as she pushed off it with her shoulder, feeling like she’d swallowed glass, feeling like if she tried to bend water it would only turn to ice. She stepped near him, close enough to shove her nose and teeth in his face, close enough to feel the improbable heat of him. Katara ignored the throbbing in her thumbs and bared her teeth at him like a posturing animal.

“So let me tell you something, right now. You make one step backward, one slip-up…” The sneer of her face made her feel stronger, feral, sharper. It made her feel like he wouldn’t be able to get past the shards this time. “Give me one reason to think you might hurt Aang, and you won’t have to worry about your destiny anymore. Because I’ll make sure your destiny ends right then and there. Permanently.”

Zuko didn’t speak, but he didn’t have to. She saw the apprehension settle over his face like a shroud, felt the rapidity of his heart and knew all she needed to know from him. Katara turned and left.

Chapter Two