In Kaien and Byakuya, Rukia could not have found two more opposing personalities. The capacity to let go of herself, her thoughts, her surroundings, her feelings, was a useful skill in battle, but she could not share her brother's distaste for emotion and affection of all kinds. In Kaien, she found warmth, friendship. A place to belong. And, within her work, a sense of camaraderie and purpose. The things she had been searching for for over a century.

It was late spring and the trees were ablaze with blossoms. Kaien was walking ahead of her on the path they always took up to a clearing to train. It had become a habit. Rukia liked the mountains and Kaien enjoyed returning to the stomping grounds of his youth. Without fail, he pointed out the pass that led to his family's mansion and the peaks he'd climbed as a child. Rukia had come to see the landscape through his eyes, every part of it holding some significance or a snatched memory.

Today though, she was relaying an anecdote from the night before: "And when I opened the screens, I distinctly saw a woman in the garden. She was dressed in white and her hair was white too, but she was young, I think. Or perhaps ageless, like a shinigami. She turned and spoke to me, but I couldn't hear what she said. I turned back inside to fetch a light and, when I looked back, she was gone."

"Did you tell Byakuya?"

"Of course!"

"And what did he say?"

"That it was impossible. That his guards would have been aware of an intruder."

"Maybe he had a nightime assignation: a visitor he didn't want to tell you about?" Kaien grinned back at her over his shoulder.

"Byakuya? Unlikely!" He chuckled as she continued: "The strange thing was that, although I could see her and she was there for sure, she didn't seem quite real. More like a vision, I suppose."

"Oh well, that is a more interesting thing altogether, Kuchiki," he said, shucking off the bags he carried in the shade of the trees. She frowned:

"You think I'm going crazy?"

"No, but your swordsmanship has improved by leaps and bounds in these past weeks, wouldn't you say?" She stared at him, puzzled by the sudden praise. "You're working much more closely with your sword now. You're beginning to understand that it's a part of you."

"I was taught that a shinigami's zanpakuto was a part of their soul."

"It's one thing to be taught something; quite another to understand what that means." He looked hard at her: "Relax, Rukia. This isn't a test. It's all about instinct." He stepped back and drew his sword smoothly. In the same instant, she realised she had shifted her weight and reached for her own. "Good," said Kaien: "That's exactly what I mean."

"But" –

"No buts."

He began. It was a little more sudden than their usual warm up, but he used the same forms and her body flowed into each stance, taking the familiar weight of his attacks on her blade. As he had taught her, she began on the defensive, testing her opponent, searching for a pattern because a pattern was a weakness. Fighting Kaien was like fighting her own shadow. She had become accustomed to his forms, yet he still had the capacity to surprise her and she underestimated him at her own peril. When she was certain he was following the standard forms of a practice session, she switched to the offensive and he graciously stepped back. He would give ground for two, three steps, and then the end of the warm up would be marked by a change in his tactics. Usually he would try to catch her off guard. Everything after that would be no holds barred to the first touch; sometimes to the first blood.

The truth was that Kaien had been no less hard on her than Byakuya and was not averse to drawing her blood. The difference was that Kaien didn't scare her the way her brother did. Behind that calm façade, she had no idea what Byakuya was capable of. Violence, most certainly. Murder on a whim? Probably not. But Kaien, she knew, would not intend her harm.

Instead of defending her next blow, he sidestepped and took two graceful steps back. It was like a dance and she let him lead because it was his lesson to teach. At first, he had been easy on her, but now it seemed they fought on a similar level. He always bested her, but she held out for longer and longer every day.

"Rupture the seas and sky, Nejibana!" he cried suddenly. As he started the incantation, Rukia unthinkingly shifted into a kido stance. It would not be the first time he had used kido in their training, but, instead of an intense burst of reiatsu, the air around her suddenly distorted and warped under immense spiritual pressure. Rukia staggered backwards.

Kaien's body was surrounded by a halo of misty white light, and she nearly cried out in alarm. It was the same light she saw when a hollow's body dissolved, yet Kaien seemed to stand taller than before, controlling the light, allowing it to flow away from him in waves that dissolved like smoke as they touched the warm afternoon air. Instead of a sword, in his right hand, he held a trident. It was pure white, a foot again as tall as the man who bore it, and yet he could lift it and spin it between his fingers as if it held no weight for him. Wide-eyed, she made no effort to defend herself. When he swung the spear next, the shaft connected with her ribs, lifting her off her feet. The blow knocked the breath from her lungs. She struck the ground, coughing.

Kaien laughed, though not unpleasantly. When she sat up, he was standing in the same place, whirling the spear in a slow circle: "Get up, Kuchiki."

"You released your sword!"

"Well-noticed."

"But the law says" –

"You can't release your sword in the sereitei. Out here" – he shrugged – "Anything goes. Anyway, for you to progress, you'll need to learn your sword release and I know of only one way to help you do that: you fight me. In shikai." He stubbed his chest with his thumb.

"I can't defeat you with my katana pre-release though!" She got to her feet: "How can I defeat you in shikai?"

"Defeat me? Kuchiki, I'm your vice-captain; I'm not asking you to win! Just fight me, the same as always."

"But if I can't reach shikai" - ?

" – You don't stand a chance." He gave a wolfish grin and stretched the arm that held the spear behind him. It began to whirl faster: "Better learn quick then."

"But Kaien-dono!" She cried as she sprang back to a distance of several spear-lengths, landing neatly on her toes: "I don't even know where to start!"

"Who was the woman in the garden last night? The one who hadn't come to see your brother?"

"How should I know?" She blocked his strike as it fell towards her head, but it was far heavier than she'd anticipated. It was all she could do to keep her own sword raised. Her knees buckled under the impact. She was forced to twist out of his way and roll away.

"You said it was like a vision!" he called after her.

She was up and running, putting a clear distance between them. He was serious then. He had never asked the impossible of her, so she needed to think: how? Many shinigami never learnt to release their swords. She stared at the katana in her hand as she ran. The idea of it changing, warping into something new, was repugnant to her. The red-bound hilt, the rough feel of it in her hand, the weight and the point where the metal hilt dug into the soft skin between her forefinger and thumb; these were the things she trusted.

But this wasn't about sentimentality. Her brother had taught her that much. If she wanted to get stronger, she had only to move forward without fear. She stopped at the edge of the clearing:

"The vision had something to do with my sword?"

"You tell me," he called to her, idly swinging the trident: "What do you remember about it?"

"That she was very beautiful."

"The woman? How did you feel?"

"Confused. I wondered why she was there."

"You said she was trying to tell you something."

"Trying to speak to me, yes."

"Could you make out any of the words?"

Rukia shook her head. He was about three spear-lengths from her now. He wasn't hurrying, just approaching with the spinning trident level with his hip. If that motion required any effort on his part, he didn't show it in his body, but she could hear the blade: a sound like rushing water. The glow had faded from his person, but she could feel him still, an imprint on the landscape, a heavier presence than he had been before: "Good," he said: "Are you starting to understand?"

"When you release your sword, you release your own spiritual pressure, but" –

"Shut up, Kuchiki. For sure, if you say 'but' one more time" - His figure blurred. He was suddenly in front of her, the trident just inches from her throat. She froze. "One more time, Kuchiki. Now, concentrate on what you saw last night. That's all that matters right now. Close your eyes."

Every nerve in her body screaming against it, she shut her eyes with the three-pronged tip of his spear just inches from her face. She opened them again, briefly and just once, when she felt the very tip of his zanpakuto touch her cheek: "Now, what do you sense from my sword?"

"Nothing," she said.

"Really?"

"The only reiatsu I sense is your own."

"And what did you sense from the woman last night."

"Nothing. But, at the same time, that didn't seem strange."

"Why would it, if the only reiatsu was your own?" She opened her eyes as he withdrew the spear: "The important thing is not what you saw last night, but how you felt. What you see is only the form your eyes choose to give something that has no form in itself." He moved around her and, as she stood rigid, he placed his left hand on her belly, just below her ribs: "I'm talking about your power, Rukia. Concentrate. Don't relax. You won't find it in silent thought." He withdrew his hand when he felt her tense and grip her sword: "Good. Now, take your stance and come at me." He stepped away.

A deep calm had pervaded her body. It seemed to come from the very centre of her and, through it, she felt every fibre of her being held in check. Until that moment, it had never occurred to her that she might be holding back. She had fought often to the point of exhaustion, but this new awareness was of something else beyond the physical constraints of her body. Another presence. Perhaps. Or a sense of stepping backwards into the embrace of something that had always been there, but which she had never cared to see.

She launched herself at Kaien. It was a ferocious attack, but, with her sword sealed and her opponent's in shikai, her every strike was countered by one ten times as powerful. Kaien parried once, then attacked with another broad swipe that knocked her sideways.

She twisted mid-air to land on her feet and lunge straight into the next attack. She could taste blood in her mouth, she realised, even as he parried, side-stepped and raised his hand: "Wait! Stop! You're hurt, Kuchiki."

She brushed the back of her hand across her mouth and it came away scarlet, but she had already moved into the next attack. He dodged her. Frustratingly fast.

"I'm fine!" she called.

"You don't look fine!"

"I'm fine!" She raised the sword again. Sprang at him. Instead of side-stepping, this time, he blocked her and twisted the spear in such a way that her sword was, of a sudden, wrenched from her grip. It went spinning across the clearing. Kaien pointed the trident towards her and, from its tip, a stream of water sprung. It struck her in the chest, washing her clean off her feet, so that she went tumbling and slipping through the long grass.

Even so, she caught herself on hands and knees and scrambled back towards her zanpakuto.

"Kuchiki!" he shouted.

She was soaked through, her clothes clinging to her back, but she wrapped her hands around the katana's hilt and faced him again. His face was serious: "I say when the lesson starts and ends. My intention was not to hurt you."

"Come at me!"

"This is a different level of fighting, Kuchiki. There's a limit to how much this power can be controlled. Why do you think shinigami use limiters in the human world? If you fight at a certain level, you can't necessarily hold back, and if I hit you with this power and you're not ready" –

"I am ready, Fukutaichou."

"You're injured and that is my fault. We finish for today."

"Show me how you did that," she said, slowly moving sideways, circling him. He continued to spin the spear casually, watching her with a mixture of caution and concern:

"Nejibana has power over water. It's the same with almost all zanpakuto; they channel the elements depending on the alignment of their bearer."

"Alignment. And yours is water?"

"Does that surprise you?"

She thought back to the first time they had trained together, how the colour of his eyes had made her think of an ocean in a storm:

"No," she said and he smiled a little at that.

"If we continue, I could put your life at risk and I'm not willing to do that. Just now, I struck you too hard. Do you understand? It is pointless to ask me to hold back or show restraint because I've already unleashed my powers. That is what shikai is. If you are not ready, you must back down because if I fight you now, I fight you at full strength."

"I'm not afraid."

"But I judge that you are not ready. If you were, your sword would have answered mine."

"Don't say that, Kaien-dono. Please don't say that." She stood still a moment, her disappointment in danger of crowding out that deep sense of calm. At such times, it was Byakuya's teachings that helped her. She had to push her own feelings aside. Her doubts were of no use to her. Self-pity, certainly, could have no place on a battlefield.

She sensed it returning; a stillness in the very centre of her body. She frowned, trying to think back to the very first time she had used kido with Renji, in the alleyways of Rukongai. The way she had been able to channel her own reiatsu. She had needed a sense of it back then. Now, she raised the katana again, concentrating on the energy centres in her wrists and the still centre in her belly.

But it wasn't enough simply to know how to channel that energy, she realised. Kaien had been trying to tell her that. All the control in the world would, in the end, be forced to surrender to one thing: her instincts.

As the thought came to her, she felt warm hands close over her own. They grasped her wrists. Pearly white. Perfectly smooth. A woman's arms encircled her body. The presence, one of warmth and light, held Rukia's arms steady, bearing the weight of the sword.

The apparition leaned forward, her head resting briefly on Rukia's shoulder as she whispered:

"Speak my name."

In that instant, every fibre of her being seemed to burn away, leaving no consciousness but that of the sword in her hands. It swept forward, the arc of the blade chased by bright white light. Kaien blocked the attack. His face was pale, his eyes wide and dark. They flicked from her to the blade she held, which was shimmering, seeming to warp and change. Slivers of energy coiled down the shaft of metal from the tip to the hilt, some breaking free and falling, crystalline, to the ground. Rukia shuddered as even more power was forced through her, coursing out of her wrists in a white light that enveloped the sword and burst forth, knocking Kaien off his feet. He landed in a crouch some yards away, his face black with anger.

The power bestowed a strange grace on her, though Rukia was no longer certain that she controlled her own movements. She swept the blade back, spinning it until it was a silvering blur at her side. When she brought it forward again, that same white light ripped through her body and down the length of the blade, towards Kaien.

The motion he made with the spear was deceptively small, but a great torrent of water burst forth from its tip, extinguishing the light and rolling on, past Rukia, and into the trees behind her. It struck them with such force that they splintered, the broken trunks and branches driven forward by a vast wave, uprooting everything in its path. As its power faded, only the smell of salt spray remained in the air. Kaien was on his feet:

"Do you understand?" he cried: "Do you understand now? Can you defend yourself against that without shikai? Stop this now, Rukia!"

But it was he who didn't understand. She was the one who was out of control. The white apparition was no longer supporting her movements. Instead, it was consuming her from the inside. She couldn't answer him. Everything she recognised as herself was already gone and all that remained, save for a deep cold in her bones, was the sword. It was trembling in her hands. If she let go of it, she was afraid that the power she was channelling would tear her apart.

"Prove it to him then," a voice whispered: "He never had any right to doubt us."

She slashed at Kaien who caught her blade against his. He had never raised his voice to her in anger, but he did now:

"Rukia! Stop!"

"I can't." Her words were cold. For the first time, he seemed to see, really see, the way her sword was trembling, changing and reforming.

"How are you" – ? He began, but she thrust her weight forward and her blade slid down the length of his spear. He sprang back before it reached his hands and span, intending to deliver another blow to her ribs with the shaft. This time though, she parried and gritted her teeth as she felt, not the impact of his zanpakuto against hers,but the collision of their spiritual forces. The ground beneath their feet shuddered and dust rose into the air, caught in the updraft of their energies. His face was close to hers, their swords crossed between them, and the anger had drained from his features, replaced by a tense concern. He spoke urgently to her over the crossed blades: "The power you're channelling is shikai; it shouldn't be possible with your sword still sealed, but you must transfer that power from your soul into the zanpakuto. Don't hold it in your body. It is a weapon. It can't be contained in anything but the released form of your sword."

The energy was cold. So cold that it seemed to freeze the blood in her veins. With every movement she was forced to shatter her body. Yet still she danced backwards with a grace that was not her own, feeling now like a puppet drawn through a storm. "Call the name of your sword, Rukia!"

But she didn't know the name of her sword.

"My name," said the woman's voice.

Tell me, she wanted to say, but no words came as she stepped forward into another attack. But, instead of following through, she span at the last moment, side-stepping Kaien's defence and bringing the sword down for a second cut. This struck home, slashing his shoulder open as he rolled away. His blood was on her sword now, and he reacted instinctively, so that, even as he eluded her, he had raised the spear and called on it. He realised, too late, what he had done.

Rukia's vision was at once filled with a wall of churning water. She heard Kaien cry out in horror. She did the only thing she could. She held her sword straight out in front of her, and called its name:

"Sode no Shirayuki," she said: "Mai." Dance.

The power that had been ravaging her body broke forth in a cold wave that, unimpeded now, flowed down her arms and into the sword. The blade turned pure white and, streaming from its tip, a beam of smokey white light coursed towards the wall of water. All this in less time than it took for her to realise what she had done.

And then the wave closed over her.

She threw up her arms to cover her head, for all the protection they might offer. But there was no crushing weight of water, no tide tearing her body to pieces. Instead, there was silence. And near complete darkness. She could hear her own breathing, could feel too the pain in her side that came with each breath. Damn that Kaien, he really had hit her hard. She tried to straighten and her head touched something smooth and hard. She reached up. Her hand came back cold and wet. To her right and left too; she was entirely surrounded by walls of ice. "Where am I?" she said aloud, but she already knew the answer. The grass beneath her feet, though now frozen and brittle, suggested she had not moved from the hillside. She was exactly where she had been only moments before, only, all around her, the water from Kaien's zanpakuto stood frozen.

In wonder, she glanced down at her own sword. It was, she saw, longer than before. Both the blade and the hilt were white and, from the pommel there hung a sheer, white ribbon. It was beautiful: "You did this," she murmured: "You couldn't have shown yourself a little sooner? I really thought we were in trouble there." She ran her hand down the blade, dusting off ice crystals that fell to the ground like a layer of new snow: "So, how do we get out of here?"

Kaien had said that his soul was aligned to water. This, Rukia realised, must mean that her own was aligned to ice. Come to think of it, she didn't feel cold and, when she put her hand against the wall of her self-created prison, she didn't have to snatch it back. Her own body, she realised, was covered with a fine dusting of frost, and there was snow in her hair. She smiled as she brushed it out.

Then she turned, touched the wall behind her and closed her eyes.

As she suspected, the ice, like her sword, was an extension of her own reiatsu. She simply willed it apart and it shattered like a pane of glass. She blinked as sunlight poured in, and then a shadow passed across the light.

Kaien reached in, took her hand and pulled her up onto a plane of frozen water that stretched from one side of the clearing to the other. The sharp pain in her side increased and she didn't stand at once, but knelt, clutching her side until she was able to breathe again without impediment. Kaien crouched down beside her:

"Ice, huh?"

"Lucky," she panted.

"Lucky?" He stared at her in disbelief: "Kuchiki, you never cease to amaze me. I could have killed you, you know. 'Lucky' doesn't even cover it."

"Very lucky."

"You're a mess."

She smiled at him and laid her sword across her knees so that he would see how it had changed. "So you worked out its name, huh? I've never seen anyone achieve shikai that way. You forced the power through your own body before you'd even released the sword. Did you even think about the danger?" She didn't answer and he put his hand on her shoulder: "Are you okay to walk?"

"Yes."

"Come on then." He helped her down off the ice: "Sure you're alright?"

"Yes."

He matched her pace as they walked back. The sun was sinking and a golden glow had suffused the forest. The leaves trembled in a high breeze, sending glittering shafts of sunlight down onto the trail. In his silence, she sensed that something was troubling him and, before they reached the edge of the forest, he stopped and turned to speak to her:

"Why?" he asked.

"Kaien-dono?"

"Why did you force that power when you knew the risks?"

She fell silent. His stormy eyes stayed on her face for a long time before he looked away, rubbed the back of his neck and laughed: "I don't understand you at all, Kuchiki." He turned and started walking again, but she remained where she stood:

"Kaien." He turned. "I didn't mean to hurt you back there. I didn't mean to cut you."

He laughed:

"Ah, Kuchiki, it would take a lot more than that to hurt me." Her face was so serious that he laughed again and beckoned her over to where he stood. As soon as she was close enough, he muzzed one hand through her hair, making her squeal and duck away. Her reaction invariably pleased him and he grinned and watched her as she swiped hair out of her face, returning it to its place.

"Please don't do that."

"Then stop looking so concerned. You didn't hurt me and even if you had" – he leaned down so that their eyes were level – "We're alright, you and me. Do you get that?"

"Y-yes."

"We're alright." He straightened and glared at the descending sun: "Okay, get moving, Kuchiki!"