Disclaimer: I don't own Bleach. I will never own Bleach. Except the kind you put in laundry.

This is the direct sequel to The Butterfly Effect. If you haven't read that, you might want to, because it's very AU, and only going to get moreso. If you're not on board for the central premise, you probably really won't like it, I gotta say. If you've already read that one: hey, awesome. Glad you're here for round two!

The Three-Body Problem

A Bleach Fanfic

Chapter One: September

"What?"

"You heard me." Urahara's voice practically dripped with his amusement. He sat casually on the basement's floor, Benihime beside him and his arms tucked into his sleeves.

Uryū half-sat, half-fell into seiza. He knew Urahara wouldn't just make a suggestion like that without a very good reason. And if they really were going to work together in all this, that explanation would be forthcoming, if he asked the right questions. "Why are you suggesting it in the first place? You can't possibly believe they'd consent to it."

The shopkeeper leaned back as Yoruichi came to sit beside him, folding herself into a crosslegged position. Their knees were an inch or two apart, at most. Placing his shoulderblades against the rock protrusion behind him, he shrugged. "Maybe they would, maybe they wouldn't. But you know, tradition is important in Soul Society, and if you can pass the test, tradition demands that you be taught. Not even the Central 46 can change that, and I'm not sure they'd want to."

Uryū fixed him with a flat look, fingertips finding the nosepiece of his glasses. "You think they want me to enroll in Shin'ō Academy? Me." He settled the spectacles higher on his bridge, letting the absurdity of the assertion speak for itself.

Apparently, Urahara didn't find it half as outlandish. "I don't think they've thought about it, particularly, but they'd jump on the opportunity, yes." He rubbed at his stubble with callused fingers, producing a soft rasping sound.

"Why? I broke into the Seireitei and helped free a prisoner slated for execution. Even if the results were good, they can't think I'm shinigami material." He nearly shuddered at the thought himself, but that was for a different part of this argument.

Urahara rolled his head to the side, giving Yoruichi a look that Uryū could not interpret.

Yoruichi herself had no such trouble. "That's true enough, but only to a point. Think about it this way, Ishida. Suppose you're in charge of a large body of soldiers, an army for a purpose you believe in to your very core. Recently, so recently it still stings, several people made a mockery of your way of doing things, proving in the space of days that your security measures are ineffective, your top officers are dangerously fallible, and there are free elements out there in the world powerful enough to pose a legitimate threat to everything you care about."

She crossed her arms over her chest, ponytail swishing as she shook her head. "It wasn't just the ryoka. It was Aizen, too. The most chaotic upheaval in the structure of your organization in at least a hundred years. What's your first priority after something like that happens?"

Uryū frowned. He'd never belonged to such a large group, and it was difficult to conceive of constantly thinking on that one scale, but she wouldn't have asked the question if she didn't think he could answer. "I'd want…" The frown deepened. Aizen, obviously. He needed to be brought down. But something else had to happen first, maybe. "I'd need to regain stability somehow. If I was going to be able to do anything else, I'd need to make sure what was left was still functional."

"Exactly." Urahara dipped his head once, eyes keen. "And the Soul Society's understanding of stability is control. They can't control Aizen right now, obviously, but…"

It dawned on him quite suddenly. "But if they thought they could control me, they would."

Urahara chuckled. "Of course they would. You're quite popular, I hear. People want to know about the ryoka who broke into the Sereitei, and while I'm sure there's been plenty of speculation about the two former captains in the group, it's not every day some member of a supposedly-exterminated tribe of humans shoots himself into the heart of Soul Society with a cannon and takes down one of its most famous captains."

Uryū opened his mouth to protest the characterization of the events, but then realized that, speaking in strict and literal terms, that was exactly what he'd done. "…I had help," he said, pinching the bridge of his nose.

"Of course. And it's better if you don't let yourself get a big head about it. But you did accomplish something any reasonable person would have thought was impossible." Urahara placed a subtle emphasis on the word reasonable that Uryū could only read as mocking.

He sighed heavily. "Fine. I suppose I can understand why no one would stop it if I tried to enter the academy. But you still haven't told me why I should."

Two sets of eyes, one silver and one gold, stared at him long enough he started to feel uncomfortable.

Clearly, he was meant to figure that one out on his own. Part of him was glad they expected him to be able to. The other part just wished they'd save him the trouble. Uryū glanced down, tapping a staccato pattern on his knee with the fingers of his left hand. He pieced together the information at his disposal: Yoruichi's mention of giving him a 'break.' The apparent understanding that he still had a role to play in whatever would happen with Aizen. His own desire to have a role in it, something which only sort of surprised him. His current and irreversible lack of power.

A conversation with Hanatarō, and another with Unohana-taichō.

"I have reiryoku," he said at last, the words heavy on his tongue. "And the place where anyone with reiryoku goes to learn what to do with it is Shin'ō."

He looked up, to find that Yoruichi was grinning, and even Urahara wore a subtle smile.

"But," Uryū amended quickly, "the two of you could just as easily teach me. Yoruichi just said there's no one better to teach me shunpō than her. Why should I go there instead of staying here?" Advocating for one set of shinigami teachers over another was really splitting hairs, but at least they were exiles, and his friends. They wouldn't try and shove obedience to the Seireitei and the Central 46 down his throat. They wouldn't know what he was and hate him for it.

Urahara's expression sobered, and he blinked slowly. When he spoke, it was with unusual solemnity. "That's true, with one major exception," he said, the words slow.

"Not even we can get you a zanpakutō."

Yuzu was tugging at her clothes again.

Karin really wanted to tell her not to do it, because her sister's nervousness was making her feel nervous, too, and that was the last thing she wanted to deal with right now. But Yuzu didn't work like that—just telling her not to worry about it would probably only make her worry more, so Karin tried to distract them both instead.

"There sure are a lot of people here," she said, crossing her arms and scanning the crowd.

There was a little bit of everyone, apparently. They stayed in clusters, though. The noble kids with their stewards or whoever was escorting them here were half a dozen tiny little knots, while the Rukongai people formed much looser, larger globs, From least to most holes in their clothes, it seemed like. A lot of them had the look of the half-starved: sunken cheeks, drawn faces, wary body language. Like a bunch of stray dogs, towards the back.

Karin preferred a stray dog to a shih tzu, though.

"There's no way they'll take everyone, is there?" Yuzu asked, her mouth turned down and eyes fixed on the people from the lower districts. She'd stopped pulling, but her fingers were bunched in the fabric of her yukata.

Karin sighed. "Nope. Too many people, not enough spots."

"Even though there's a war coming?" Yuzu's eyes swung back towards her.

She shrugged, tipping back on her heels until she felt the rough press of bark from the tree behind her through the fabric of her gi. "Even with that, they're not gonna care about a few kids with almost no reiryoku. If anything, they'll be stricter, so they can throw more energy into training people who might be strong enough in time to do something useful."

Everyone knew that they had eight years left, which meant that this year's academy class would be one of the last to have a full six-year course before things got bad. Karin clicked her tongue against her teeth and unfolded her arms, scratching her cheek.

"Guess we gotta get in line. Have you seen dad?" It was never good to lose track of the old bastard.

"He said he'd be waiting for us nearby. I think he didn't want to cause a—"

Yuzu was cut off by a shout from somewhere to their left. Both girls turned to face it, Karin taking half a step in front of her sister.

It didn't take long for the shouting to become a full-blown commotion, and Karin wondered if someone hadn't spotted the geezer after all. "Come on, Yuzu… let's go get him out of there."

Their father, big idiot that he was, would never do something like force his way out of a crowd, but Karin had no such compunctions. With Yuzu following close behind, she started to move people aside, mostly with her elbows and shoulders, forcing the two of them to the front edge of the crowd.

"What the—?"

People were in fact gathering to get a look at someone, but it wasn't their old man at all. Instead, it was some skinny guy in mostly white, wearing glasses and a scowl that impressed even her. He looked kind of familiar, though…

"Ishida-san!" Yuzu called from behind her, and Karin turned back over her shoulder to see her sister wave a frantic hand at the person in question. Taking a second look at him, she had to agree. This was definitely that kid who'd broken into the Seireitei with their dad—but what the hell was he doing here?

Karin decided it really didn't matter much. "Hey, give him some space, morons!" She threw a few more elbows to make room, and Yuzu slipped in under her, grabbing Ishida's sleeve and pulling him through the opening Karin had created. Someone at the other side of the crowd was trying to disperse it; probably one of the exam officers, but they got away before he reached them, ducking into a nearby alley.

"Are you okay, Ishida-san?" Yuzu asked, while Karin glared out the alleyway, deciding that they hadn't been followed. Pretty much everyone was going back to where they'd been, but no few clusters were now deep in conversation, heads bowed. The expressions ranged from mild interest to excitement to some outright hostility, but that didn't surprise her.

"Er… yes, thank you, Yuzu-san." Karin turned her back to the crowd, watching Ishida brush off his sleeves with a distinct air of the uncomfortable.

"If you didn't want to get gawked at, you probably shouldn't have worn the outfit that says 'look at me, I'm a Quincy,'" she pointed out flatly.

Ishida grimaced. "I… hadn't anticipated this level of recognition," he admitted, his face coloring slightly.

"Dude, you're famous here. Like… really famous. They did a whole issue on the ryoka in the Seireitei's newspaper thing. Bootleg copies of that make it out into the Rukongai all the time."

"Though in fairness, the pictures they have are kind of bad. You'll probably be okay in the future if you wear a different color." Yuzu offered a smile, but it didn't seem to do much to put Ishida to rights.

He looked down at himself, his expression flattening out until Karin couldn't tell what he was thinking.

"I'm not ashamed," he said quietly, and Karin blinked.

Yuzu backpedaled. "I didn't mean to imply that you should be," she said quickly. "It's just… unless you want that kind of attentioneverywhere you go, you might want to think about it, is all."

He appeared to consider that, then nodded. "I suppose if I pass the exams, I'll have to wear a uniform anyway."

"Wait. You're here to take the exams?" Karin looked at him with raised brows. He'd sounded barely tolerant of the idea of the academy's existence last time they'd talked about it.

"…Yes."

She had a feeling she wasn't going to get much more out of him than that at this point.

Yuzu chewed her lip thoughtfully. "Do you have an exam number yet?"

"A what? I just got here—Yoruichi didn't really tell me anything about—"

"Did I hear someone call my name?"

All three of them glanced up at the slightly-muffled masculine voice, and Karin immediately spotted the black cat poking its head over the side of the roof overhang above them.

Yoruichi had something in her mouth; upon closer inspection it looked like one of the number chips Karin and Yuzu had retrieved from the exam registration desk a while ago.

"Catch, Ishida."

The object fell, turning around in the air and glinting in the sunlight for half a second before he snatched it out of the air, opening his hand and staring down at it.

135—he was about fifty people after her and Yuzu.

"I went ahead and registered while you had your little meet and greet with your fans." She jumped down from her spot on the roof, landing lightly on his shoulder, apparently completely unaffected by the fact that he was trying to set her on fire with his eyes.

"You could have warned me about that."

"And spoil the fun of watching you get mobbed? Not likely."

Ishida sighed deeply, then turned to Karin. "Any idea what the exams entail?"

She shook her head, rippling her short ponytail with the motion. "Nope. Apparently it's some big secret, because dad wouldn't tell us either." And he'd gone to the academy, the jerk.

Everyone turned to Yoruichi, who took that as her cue to hop from Ishida's shoulder to the ground. "I wouldn't want to ruin the surprise," she said lightly, swishing her tail. "I'm just going to go see Isshin. Come find us when you're all done, okay?"

"Number 76, please."

Yuzu sucked in a deep breath. They'd called Karin in a couple of minutes ago, but she still hadn't emerged from her examination, and 76 was Yuzu's number. Swallowing, she got to her feet, chewing her lip.

Glancing back towards Ishida, who had elected not to stand in the orderly line that had formed, she held up her token. "Guess I'm being called."

He blinked at her, then nodded. "You'll do fine."

She didn't ask him how he knew that, accepting the gesture for what it was. "I'll see you soon, Ishida-san." Turning from him, she hurried towards the long booth where the examination officials sat, approaching the one who'd called for her and handing over her polished wooden token.

The man added it to a box of them with a clink, making a note on his clipboard, then glanced up at her. "Inside, to the left. The room marked four."

Yuzu, disinclined to ask any more questions of someone so brusque, skittered past the booth and inside the building it was set up in front of. There was only one testing location that she knew of, and it was here, in the eighth district of the Rukongai. This one unassuming building had been the first step on countless journeys to the Seireitei and the Gotei 13. And the last step on many, many more than that.

She was probably imagining the mild feeling of foreboding that came over her as soon as she stepped across the threshold, but the shakiness of her breaths and the uncomfortable stirring in her stomach were very real. Taking the path to the left, she counted the doors until she came to the one marked 'four.'

There was no one standing outside it, and the door was shut.

Tentatively, she raised her hand to knock, only to have it slide open in front of her closed fist. A tall woman stood behind it, tipping her head to look down her nose at Yuzu. She wore bandage-wraps from her knuckles to her elbows, and a sleeveless version of the standard shihakushō. Her brown hair was tied into a tail high on her head, but thick enough that strands of it splashed over her shoulders anyway, doing nothing to soften the coarse lines of her face, nor the completely-obvious skepticism in her expression.

She stepped aside though, gesturing with one hand for Yuzu to enter.

There were two tables set up in the room, one longer than the other. In front was the shorter one, and it was low to the ground, a cushion resting before it and what looked like an ordinary sword on top, held up with a small display stand. Behind that by half a dozen feet and elevated was the second table. Two other people sat there, a mild-looking man with an eyepatch and a woman with no discernible expression and a fastidiously-neat bun.

The first woman moved back to lean against the examiners' table, crossing her arms over her chest. "Sit," she said crisply, and Yuzu could only assume she meant at the cushion in front of the first table, so she took a few steps forward and lowered herself into seiza.

"What's your name?" asked the man with the eyepatch, a brush poised above the stack of paper in front of him.

"Yuzuki Kurosaki, sir," she replied, using the more formal version of her name. She somehow doubted they were interested in what she went by.

Both he and the second woman made a note, and then the first lady spoke.

"Well, Kurosaki-kun, the exam is pretty simple. If you pass the first part, we give you the second one. Start by touching that asauchi there."

Touching it? Yuzu blinked, but obeyed, reaching forward very carefully and extending a single index digit, which she laid carefully on the tsuba of the sword.

The result was instantaneous. She felt something being pulled out of her, and her whole body jerked forward slightly. A flare of light forced her to shut her eyes, but she didn't break contact with the blade, fairly certain that she couldn't have even if she'd tried.

After a few seconds, the pulling sensation ceased, and she felt oddly drained, like all her parts were too heavy. Blinking her eyes open, she gasped when she laid eyes on the blade. It had been a standard katana a few seconds ago, but now she was looking at a tantō, the blade of which was slightly shorter than her forearm. The hilt's wrapping had changed color, to a saturated violet, and the metal parts were all silver-looking, including the tsuba, which had a six-pointed shape that reminded her strongly of petals.

She took her finger from it quickly, looking with wide eyes up at the examiners. The man was smiling slightly, and the woman with the bun nodded once, both taking notes still. The woman in the center cocked her head, a birdlike gesture, then shrugged.

"Nice work. Stand up and c'mere for a second."

Yuzu scrambled to comply, clambering to her feet and giving the table a wide berth on the way to stand in front of the examiners. She couldn't help but glance back at the tantō, though.

"Here."

Her attention snapped back to the woman with the ponytail, who held out what looked like a glass orb, probably the size of a small cantaloupe.

"That the zanpakutō reacted that way means you have enough reiryoku to attend the academy. But it's not a very good measure of just how much. That's what this is for. Just hold it with both hands."

Yuzu took it carefully, half-expecting an explosion or some other uncomfortable sensation, holding it near the bottom but away from her body, her hands slightly apart and fingers fanned wide.

The main examiner huffed, and shook her head. "It's not going to kill you, Kurosaki-kun."

And indeed it did not. Rather, the orb slowly turned colors, like someone had dropped a splash of dye into it, only the dye was coming from Yuzu's fingertips. It was magenta-pink, and swirled around inside the orb as if it were a curl of smoke from her father's pipe, thickening and darkening at the same time.

"Huh. Looks like we've got an eight."

The woman sounded a bit impressed, maybe, though Yuzu had no idea why. She wasn't actually doing anything, as far as she could tell. But the rasp of brushes on paper informed her that this was going into her notes as well.

"All right, Kurosaki-kun," the woman said, grasping the top of the orb and removing it from her hands. "Move-in day is next week. Class listings will be posted by noon, so you'll want to check those. You'll get your zanpakutō back when you show up for zanjutsu class on your first day, which is the day after you move in, so…" She frowned and turned to the male examiner.

"October second," he said, and the woman nodded.

"Right. Until then, we'll hold onto it for you. You're dismissed."

It took a full five heartbeats for Yuzu to actually process that. She… she'd been accepted? Her eyes rounded, and her lips parted before she realized she had no idea what to say.

"Um…" It occurred to her she'd also been dismissed already, and her face flushed when the examiner raised an eyebrow at her. "Thank you!" she added hastily, bowing deeply and turning around to flee the room as fast as could still be considered polite.

Out in the hallway, she planted her back against the wall and took several calming breaths. She'd passed.

She'd actually passed.

It was, she observed, a very bad time to be having second thoughts.

Dinner at the Kurosaki house was a green curry he hadn't tried before. When the spice hit the back of his tongue, Uryū had to admit, if only to himself, that even he could take a few culinary lessons from Yuzu.

"So…? Don't leave us hanging here." Yoruichi looked between the three of them, her eyes landing on him last of all.

Uryū swallowed. "What else do you want to know? We all passed, and we have no idea what classes we're in for another week." He picked up a knuckle-sized ball of rice and coated it lightly in the curry.

"Well, there's more to it than that, right?" Isshin, pausing in the middle of shoveling another bite into his mouth, set his bowl down and grabbed his cup of tea. "They gave you an asauchi, right? And then did the thing with the glass ball?"

Across the table, Karin nodded, swallowing audibly. She flinched as her bite went down, a sure sign she'd been a bit hasty in doing so. "Mine stayed a katana, but the hilt turned this really bright red, and the metal parts look coppery or something, I dunno." She shrugged, but didn't seem to quite be able to manage her normal blasé expression. Uryū thought she might be on the verge of a smile, even.

Yuzu was a bit more subdued. "What was that orb thing, anyway?" she asked, nibbling at some snap peas.

"It's called a Kikeisoku," Yoruichi replied. "It's a device that measures the concentration of reiryoku in whoever is touching it. Kisuke invented it… probably a hundred and twenty years ago now? The placement part of the exams used to be a lot more indirect, because of the difference between how much reiryoku a person has and how much of it can be felt as reiatsu."

"Isn't that a crude way of trying to decide who belongs in an accelerated class?" Uryū asked, shifting slightly in his seat. "People can expand their pools of reiryoku, can't they?"

"Yes, but it's not easy. And generally speaking, people who start out with the most end up with the most as well. It's not the only measure of someone's potential, but it's the best single indicator. After that, hard work has to take care of the rest."

He was tempted to say something about confirmation bias—of course they'd end up better off in the end if they had the best instruction. He only shook his head instead.

"They said something about 'eight' when I did that part," Karin said. "Is that like… eight out of ten or what?"

"Out of twenty-five," Isshin said. "But in the reverse order. One's the highest, not the lowest." He grinned widely. "Most fukutaichō-class shinigami are around six or so."

"The scale's bottom-heavy," said Yoruichi. "You have to rate a fifteen to make Shin'ō, and only five percent of applicants can do that much."

Uryū pursed his lips. "Presumably, the instance in the general population is even smaller."

Isshin nodded. "It is. The vast majority of souls within Soul Society don't have much reiryoku at all. Some historian at the academy did a survey once, and taught it to my medicine class. I think it was… something like eighty percent of people are right at twenty five? Anyway, it makes healing them harder, because you can't use their reiryoku to accelerate it if they don't have any."

"Someone will probably teach all of this to you at some point," Yoruichi said. "In addition to your four practicum classes, you have the mandatory history lectures and optional classes on a bunch of other things. I think each division, plus the Onmitsukidō and Kidō Corps, publish a list of what they recommend if you want to be best-qualified for a position with them."

"Yeah," Isshin agreed, "except half of them pretty much tell you to do whatever. Unless you're looking outside the Gotei 13 or at the Fourth or Second, no one really cares what you do."

Yoruichi snorted into her tea. "Which was fortunate for you, since you skipped everything but your health lectures and practica, if I remember the story."

"Yeah, because everything else was boring." Isshin paused for a moment, blinked, and sputtered a little. "But, uh… you girls should go to all your classes and do your best. You too, Ishida!" He clapped a large hand on Uryū's shoulder, forcing him forward slightly under the sheer weight of it.

Karin rolled her eyes, and Yuzu gave him a sympathetic look.

"If you say so," Uryū said, going for diplomacy.

Yoruichi found him on the porch later that evening.

The Kurosakis had a small garden along the side of their house, the opposite direction from the attached clinic, and for lack of anything else to do, he sat on the wooden floor and stared blankly out at the flowers.

"What's eating you?" She was a cat again, and flopped herself down next to him.

He hesitated. "I understand why I'm doing this."

"There's a 'but' there."

Uryū sighed. For several moments, he let the silence permeate and gathered his thoughts. "I understand it, and I'm willing to go along with this because the two of you think it's going to make a difference, but…"

His memories of that day were hazy—he'd just been a child, after all. But he knew what had happened. He knew why his grandfather had died.

"Somewhere in there is the person or people responsible for what happened. What if I end up… what if I encounter them? What if I don't? Is it… am I betraying his memory to even go at all?" Uryū pressed a fist to his sternum, rubbing hard at the spot through the fabric of his shirt.

"I didn't know Sōken very well at all," Yoruichi said, the very end of her tail curling up and down slowly. "So I can't answer that for you. But I think you should ask yourself what kind of person he was, and what kind of person he wanted you to be, and let that be your answer."

Uryū felt a fraction of the tension bleed out of his shoulders. "I thought you might say that."

"Did it help?"

"…It's enough."

Term Dictionary:

Kikeisoku –気計測 – "Spirit Measure." A device invented by Urahara to detect the level of reiryoku in a soul. More accurate than usual spirit perception, which senses reiatsu, which can be suppressed and exuded at different percentage rates between people. The amount and thickness of the color in the orb corresponds to a scale of reiryoku classes, from 1-25. Denser, more saturated smoke indicates more reiryoku, but the color just corresponds to the actual color of that person's energy. I made this up, but it's at least consistent with canon, where supposedly Kaien Shiba's reiryoku was "sixth class" when he went into the academy, which was the level you'd expect of a lieutenant. Yuzu and Karin are both eighth-class, which would easily match the reiryoku levels of the average single-digit-seat officer, but as Uryū rightly points out, other factors play in to how effective someone is as a shinigami.

This chapter was a lot of setup, and a lot of me spilling headcanon everywhere, since there's really no information on exactly what the entrance exams for Shin'ō consist of. Also extrapolating on exactly how zanpakutō change sealed forms (like whether they're wakizashi or katana or whatever), since we see a lot of divergence even in those between shinigami. In case it wasn't obvious, the canon divergence gets serious here.

Also, I know that canon!Yuzu's name is not really Yuzuki. I changed it because it always just kind of sounded like a nickname to me. I expect it will almost never matter.

It occurred to me halfway through plotting this that it is, if you squint, a high school fic. I'm going to try really hard not to make it feel like one, but the whole 'work through your issues with your zanpakutō thing is just begging for some character study, and I can't resist.

Reviews desired but not required.