Undergoing rewrite on AO3 (link in profile).

Chapter 11.2

'Got them.'

Yoruichi breathed out quietly, allowing her shoulders to sag slightly. 'How are they?'

'Suì-Fēng-san is unconscious, but otherwise seems stable. Tsuzuki…' Kisuke's voice faded out for a moment before coming back. 'Probably best if you send for a palanquin.'

She wouldn't let her heart skip. She wouldn't. Kisuke didn't ask her to send for Unohana, but she didn't like the hesitation in his tone, especially when coupled with Tsuzuki's last message that Aizen might be involved.

'Also, I'd like to apply for a few days' leave. I have some suspicions about this poison.'

No, she didn't like it at all.

'Consider it done.'

Kisuke yanked the kimono away from Tsuzuki's leg, lips thinning as he saw the bloody mess and the white of bone.

"You can't feel it?"

Leaning back against a tree trunk, Tsuzuki too was staring at his own leg, brown eyes slightly glassy. "I didn't even know I was injured?" It came out as half a question instead of a statement, and he looked confused at his own proclamation. His hand glowed green as he ran it slowly along his calf, and there was the sound of bones grinding together as they shifted back into their original alignment.

The former shopkeeper's frown deepened. Adrenaline alone should not be able to account for this phenomenon – he eyed the leg closer – yes, that was definitely one of the main arteries in the leg. Any higher, and it would have hit the popliteal artery, which was likely the original target of the attack. A strike directly upwards from the ground, then? Compartmentalising that thought for later consideration, he returned to the mystery at hand.

It was highly unlikely that Tsuzuki had managed to completely miss such a deep gash due by accident. Even if his adrenaline rush had dulled the pain, it wouldn't have removed it completely. The statistical likelihood of the attack managing to severe all nerves in the area was too low to be a feasible hypothesis. This left –

"Did you check for poison?"

Tsuzuki stilled. His eyes fell shut and then opened again in a slow blink, and Kisuke was beginning to grow alarmed by the way his eyes couldn't seem to focus, the way his breathing was far faster than it rightfully should be.

"Raise your body temperature, you're going into shock," he hissed.

"I did!" Tsuzuki protested, looking insulted.

Unconvinced, Kisuke laid a hand over the pulse in his throat, checking his heart rate and core temperature at the same time. "You're freezing cold," he disagreed. A nerve agent coupled with a numbing agent, perhaps? That would explain the overall disorientation and lack of sensation.

Definitely not a typical poison you could buy on the black market.

'Yoruichi-san, I think we're going to need that palanquin sooner than later. And Tessai-san too.'

Isshin's eyes flitted to the Shihōin palanquin as it appeared in view, unremarkable in its presence amidst all the other palanquins, except for the fact that he knew the Shihōin princess. He was quite sure that Yoruichi had been uninjured, given that she had been right beside him for most of the battle, helping to keep the Dankū barriers raised. Unlike some of the other nobles in attendance, she wouldn't summon her own palanquin without a very good reason.

"Urahara-san, can I speak to you for a moment?"

Walking next to the palanquin in full view – another oddity, he had never known Urahara Kisuke to openly flaunt his presence in such a manner – the former shopkeeper turned his head at the sound of Isshin's quiet voice. The blond gave him a slight nod, casting his gaze back to the guard retinue surrounding them.

Shihōin Katsuo slipped out from amongst the guards, zanpakutō on full display as he took over Kisuke's position.

"On behalf of my clan, I wish to extend our gratitude to Shihōin Tsuzuki-dono for his invaluable aid in retrieving my errant nephew." His mouth was running on autopilot, even as alarm bells rang inside his head. Even though Kisuke was standing right in front of him, he could just barely sense the other man, and it was more like the faint impression of an echo than the reiatsu of a living person. What was Kisuke doing in high alert mode when the battle was – as far as he could see – over?

The blond eyed him contemplatively, and then he must have loosened the control on his reiatsu a fraction, for he could sense a tendril of crimson mist uncurling, just enough for him to grasp it gratefully.

"No gratitude is necessary," Kisuke replied formally. 'Tsuzuki will be fine; physically, just a broken leg. Tessai-san is tending to him now.'

Isshin bowed properly at forty-five degrees, far lower than a captain should to a third seat, to convey the depth of his appreciation, even as he breathed an inward sigh of relief. The next sentence, however, had him tensing subtly.

'We suspect Aizen's involvement.'

He scrambled for a way to continue the conversation, to deflect the suspicion of two strangers – as far as everyone else knew – standing together in silence.

"How is Shiba-kun?" asked Kisuke abruptly. Then, as Isshin blinked dumbly at him, he added, "Tsuzuki will no doubt wish to know."

'The poison coating the attackers' blades appears to be custom-made. I'll have to run some tests to be sure.'

Isshin's eyebrows shot up at the lack of an honorific appended to Tsuzuki's name – in public, no less. "Ganjū-chan will be fine," he replied. "Kaien and Kūkaku are chewing him out thoroughly at the moment for sneaking off to play at the riverbank without telling anyone. If Byakuya-kun hadn't noticed him wandering off and followed him, then purposefully drawn the enemy's attention…" he trailed off. It was not hard to envision the end result of the spirit equivalent of a six-year-old against them. Byakuya, who was nearly a century old, at least knew to keep quiet and keep his struggling to a minimum. 'Let me know how your investigation goes? I don't remember this event ever having occurred.'

Kisuke inclined his head in slight agreement with both of Isshin's assessments. 'I'll keep you posted.'

He must have drifted to sleep after a while, lulled by the swaying of the palanquin and the healing process, for the next time he opened his eyes he was in his own room back at the Manor.

"We've been complacent." He had never hear Kisuke's voice in that particular tone before. Tsuzuki pushed himself up slowly, carefully. Were they talking about Aizen?

"Isshin mentioned, and I agree, that this didn't happen the last time around."

An icy feeling ran down Tsuzuki's back, and he lurched the last few paces back into full consciousness, the words falling out of his mouth before he could stop it. "So it's because of me then?"

"If you want to think of it that way," Kisuke replied bluntly, without looking at him.

He wasn't going to examine the roiling mix of guilt and horror rising in his gut. "I'm the only thing that changed," Tsuzuki argued. He saw Kisuke begin to turn in his direction, a frown beginning to mar his brow, and the blond had just opened his mouth to speak when he was interrupted.

Yoruichi turned from the window, her features grim, a Hell Butterfly fluttering from her finger. "I've just gotten confirmation of their identities. It is them," she added ominously.

"Then they're several decades early." All of Kisuke's attention was back on her, Tsuzuki seemingly forgotten for the moment.

Another Hell Butterfly flitted through the open window. "The captives are talking about a mysterious benefactor." Even in the dim moonlight, Yoruichi's face was noticeable paler.

Kisuke growled, his reiatsu flashing visibly for a moment, painting the walls blood red. "Aizen."

Already Yoruichi was shaking her head. "We can't prove it."

The blond turned to her, and very deliberately raised an eyebrow. "We?"

Yoruichi looked sharply at him, rising on her tip-toes to put her closer to Kisuke's eye level. "You will stay out of this. We can't afford to draw any more of Aizen's attention if you want Tsuzuki to have a chance at successfully infiltrating Aizen's inner circle." She held out a hand for the next Hell Butterfly, cocking her head to a voice only she could hear. "Check South Rukongai District Forty-Two," she instructed. "There's a row of abandoned warehouses on the western edge, near the cliffs."

Tsuzuki watched the latest Hell Butterfly depart, momentarily distracted from his own thoughts. "Wouldn't they question how you knew about their base of operations?"

"No one will ask how the head of intelligence and covert operations comes by her information," Yoruichi answered drily. She turned back to Kisuke. "I've gotten a sample of the poison delivered."

With a single sharp nod, the blond was gone from the room.

It was lunch two days later when Kisuke reappeared, ignoring the others scattered about the room and making a beeline for Yoruichi. Sitting opposite her, Tsuzuki sat up straighter, dropping all pretence of eating his food.

"Artificial anti-coagulant," he spat, holding up a vial of colourless liquid. "Mixed with a slow-acting nerve agent, a local anaesthetic, and mild paralytic specially designed not to interact with any of the other chemicals. The combination ensures people won't even notice they were hit and slows their reaction speed, but not sufficiently to normally warrant an in-depth post-mortem investigation."

Yoruichi nodded, dropping her chopsticks carelessly on the table and rising from her seat. "On its own, is it lethal?"

"No," the blond sighed, giving the vial a shake. "If you hadn't noticed the wet sheen on their weapons, we likely wouldn't even have realised that they were using poison."

Her gaze cut to Katsuo, seated several places away from Tsuzuki, and like the rest of the room had long ceased any pretence of interest in his food. "In your professional opinion, what is the likelihood that such a mixture was found on the black market?"

"Absolutely impossible," the commander of the Executive Militia replied immediately, without even pausing to consider it.

Yoruichi simply nodded again, likely having expected as much. "Then we can conclude that it came from their unknown benefactor. Are you aware of any individuals capable of creating such a concoction?"

Katsuo didn't respond verbally, but his gaze slid sideways subtly and he arched an eyebrow almost incredulously, as though wondering why she was even asking him that question.

Kisuke raised an eyebrow right back.

Yoruichi rolled her eyes. "Anyone else," she stressed, arms folded.

There was a significantly longer pause as Katsuo gave the matter his full consideration. "Hikifune Kirio-taichō, Unohana Retsu-taichō, Yamada Seinosuke-fukutaichō, Akon Fumishō-jū-roku-seki, Nakatomi Junko-dono, Hoshino Hisoka-san, Shiba Kūkaku-dono, and known criminal at large Kurotsuchi Mayuri," he finally stated.

Yoruichi stilled, expression turning completely serious.

"Kisuke, I want a comprehensive list of all the components, and a list of possible suppliers for the more exotic. Suì-Fēng, inform Ōmaeda-fukutaichō that I want to see her in my office after lunch."

Suì-Fēng bounced to her feet, not a single hesitation in her step. Tsuzuki was glad to see that she seemed to have completely recovered from being knocked unconscious during the melee two days ago, and then accidentally thrown into a tree – not that anyone had told her the last part.

The blond spun on his heel and followed the two of them out, but not before leaving a parting message.

'I'll talk to you tonight.'

Tsuzuki watched the doorway through which they had exited, trying to organise his thoughts in order. Kisuke likely wanted to know why he had put out an alert for Aizen. What had seemed so obvious during the battle itself – he couldn't see that bowman, couldn't even sense him, even though he had to be standing right there according to the trajectory of the arrow, and it had reminded him starkly of Aizen's invisibility kidō that had erased even reiatsu signatures – was no longer as apparent now. What if he had been mistaken? He had gotten poisoned some time during the battle, what if it had been messing with his senses even then?

He suddenly realised that someone had been speaking to him.

"My apologies, could you repeat that please?"

Katsuo frowned at him, but obliged. "At the start of the battle, when that Kuchiki brat was kidnapped, how did you know Urahara-san was there?"

Tsuzuki blinked at the former clan heir. "Where else would he be?"

"Huh," muttered Katsuo thoughtfully, turning back to his food.

Tsuzuki stared at his side profile. What did that even mean? Urgh, why did everyone have to be so cryptic?

It was so late that it could be considered early when the blond finally turned up in his room. Tsuzuki jolted awake when the proximity alert ward triggered, hand scrabbling for his zanpakutō, before realising belatedly that the intruder wards were still silent. Sending out a quick pulse of reiatsu to silence the proximity ward, he sat up, shivering slightly as a cold breeze came through the open window.

Kisuke was leaning against the wall, eyes shadowed behind his open fan. The cool sensation of a privacy ward flowed over his skin – better to be safe than sorry, even in the middle of the Manor – before the former shopkeeper spoke. "Tell me what you sensed."

Haltingly, Tsuzuki narrated his suspicions, voice growing smaller and smaller as Kisuke didn't say a word, neither to disparage him nor to encourage him.

The fan snapped shut when Tsuzuki finally trailed off, unable to continue any further.

"This, insofar as we could gather, was the situation. Shiba Ganjū, as young children are wont to do, had become bored of the flower-gazing, and had sneaked off alone to explore. Kuchiki Byakuya, noticing him leave, followed behind and was able to catch up at the riverbank. They were thus the first to spot the enemy's approach via the river, using hollowed reeds as breathing tubes. Knowing that they couldn't escape before they were seen, Kuchiki-san hid Shiba-kun amongst the reeds, and drew the enemy's attention to himself. He was captured and brought with the intention of being exchanged for his father for better leverage."

Tsuzuki nodded, absorbing the new information. There was no need to repeat what had come next.

"Their first mistake was not checking that the sword you had dropped was in fact your zanpakutō."

"No," interjected Tsuzuki quietly. "Their first mistake was not making sure they had everyone accounted for."

He could have sworn a quicksilver of a smile tugged at Kisuke's lips. "To be fair to them," acknowledged the blond, "it would be difficult to confirm visual contact on eighty-four individuals."

"It was an exact replica of my zanpakutō," countered Tsuzuki, though Kisuke had already known that. After all, he had been the one who had gotten it custom-forged as a birthday gift for Tsuzuki. "They were hardly going to ask me to release shikai as proof." Wasn't that the exact reason why it was the perfect decoy?

The blond conceded the point with a slight incline of his head. "When you had not appeared with the other shinigami fleeing towards the Nakatomi's barrier, Yoruichi contacted me. I spent some time tracking echoes of your reiatsu all across the field before finding you at the edge of the sakura trees."

Tsuzuki winced slightly at the reminder. He didn't remember much of the immediate aftermath of the battle, just vague impression – Kisuke calling his name, being helped into a palanquin together with Suì-Fēng, Tessai's cool green reiatsu.

"Was there any period of time when you had been distracted, for instance by a severe injury?"

He thought hard, frowning as he tried to dredge up distinct events in the blur of the battle. "Yes," he replied in surprise. "On my way to find Suì-Fēng, a burst of fireworks too close destroyed my entire right ear, including the semi-circular canals of the inner ear. The disorientation from the damage to my vestibulocochlear system prevented me from focusing on anything else until it healed."

"You were likely poisoned during that time," concluded Kisuke. "The strike had been aimed upwards, from the ground, and given your habit of monitoring your own status it was unlikely that you managed to miss the initial injury to your own person otherwise."

He had to ask. "Do you think it was Aizen?"

Kisuke closed his eyes and tilted his head backwards, fan tapping at his upper lip. It was a long moment before he answered, words careful. "That is the most likely explanation. However, we cannot discount the slim possibility that it had been another individual, especially given that Kurotsuchi-san at present would have both the capability and the resources to perform such a feat. Right now, Yoruichi is tracking down possible suppliers for independent confirmation."

Tsuzuki watched him carefully. "You don't think she'll find anything."

The blond snorted, a shadow flitting across his face. "If it were Aizen-san, there will be nothing to find."

A snatch of conversation, half-remembered from that first night, surfaced. "Did you already know who the perpetuators were?"

The tapping of the fan stopped.

"When we said this did not happen the last time, it wasn't fully accurate," Kisuke finally explained. "There was an attack by these very same perpetuators, except that this time around, it happened thirty-five years too early."

He did a quick calculation in his head. Thirty-five years… "After your exile," he spoke aloud thoughtlessly, and immediately wanted to hit himself for his tactlessness.

Kisuke barely blinked, but he had known him for too long to be fooled by the lack of an outward reaction, especially in a trained assassin. Soul Society's betrayal had left a deep scar on the exiled shinigami, and even Yoruichi – who had left of her own free will and had never been officially branded – rarely did more than allude to it.

"Indeed," the other man murmured tonelessly, before he could figure out how to even begin apologising. "And therefore my information is second-hand. From what Yoruichi managed to gather, they had attacked during a cherry blossom viewing, much like this one. No one had checked for the presence of poison, so we cannot be absolutely certain that it had not been present. The most significant difference, however," and he straightened, giving Tsuzuki his fullest attention, "is that previously, Byakuya's parents did not survive."

It took Tsuzuki several moments to remember how to form words again. They had barely been back seven years, and already there were drastic changes in their future. How were they going to survive the century?

"I am starting to suspect our presence has already made greater waves than we have ever thought possible," Kisuke informed him sombrely. "Our foreknowledge will soon be rendered completely useless."

He breathed out quietly. "You need information," he repeated, partly as a reminder to himself, partly to confirm what Kisuke was implying.

"Can you do it?"

It wouldn't be easy, he knew. The mere thought of Aizen, the memories of watching his friends and acquaintances die one by one, directly or indirectly to him, made a pit of rage bubbling in his gut. He clamped down on his reiatsu forcefully, fighting to mask his turbulent emotions. Could he play his part well enough to fool the master of deception himself?

By all means, it should have been impossible. Sending Kurosaki Ichigo on an infiltration mission? He would have blown his cover at the first sight of depravity Aizen displayed. Unlike Ichimaru Gin, he had always had a very strong moral code, and an inability to control his own emotions.

But he wasn't that naïve child anymore. He was stronger, used his brain more, and perhaps most importantly he understood there were greater things at stake. Running his mouth and swinging around a gigantic sword wouldn't save everyone, he'd seen that once already. However, he didn't have to turn into Ichimaru, didn't have to turn a blind eye to Aizen's machinations in an effort to gain his trust, didn't have to try to do everything alone. As Yoruichi had mentioned once, he, too, had a tactical genius on his side. One who's cryptic and melodramatic – though he hadn't seen that side of Kisuke for a while, not since the Visoreds' deaths – and often preferred to let him fumble in the dark, true, but on his side. If Urahara Kisuke could train a human boy to fight on par with Zaraki Kenpachi – albeit using the man's hubris against him – in three days, he could figure out a way to defeat Aizen. All Tsuzuki had to do was provide him with the means to do so.

The word 'impossible' had never been in his vocabulary, and it wouldn't start now.

He met grey eyes calmly. "Yes."

Studying the blond closely, he suddenly became aware of the faint bags under his eyes, the prominence of his stubble, and how his slouch against the wall seemed less deliberate and more out of actual fatigue. Normally Kisuke took great pains to keep up his mask of being a lazy carefree idiot, and that included looking the part.

"Have you slept at all since that night? Or –" he remembered lunch that day, how Kisuke had walked out minutes after he entered without even looking at the food "– eaten anything?"

"We need to track the leads before they go cold."

That was a 'no', then. From what the other man was implying, he wasn't the only one – so, Yoruichi too, then? Perhaps even Katsuo?

And what had he been doing the past two days?

Kisuke must have caught the change in his expression, for he was interrupted before his thoughts could go very far. "You were healing from a major injury, and this is not your area of expertise."

"I should still have done something," he insisted. After all, it was his –

"– fault?" asked the blond, and for a moment he wondered if Kisuke could actually read his mind. As if to prove his point, Kisuke rolled his eyes. "It's written all over your face. Yes, it is likely that our presence is what caused this event to deviate from the one we know of, but it is hardly your fault. With this strike, Aizen-san can achieve multiple objectives. First, he could evaluate your character, and see if he can recruit you to his cause. Second, he could evaluate the capabilities of many of the top shinigami in the Gotei Thirteen, learn their habits, perhaps even their shikai abilities. If he had been present at the battle, then you were right to keep your shikai special abilities hidden. And last, if any of them had died, especially any of the clan heirs or the Hashiji baby, it would only serve to sow discord amongst the noble clans and pave the way for his takeover."

It didn't ease the guilt churning in his chest, not exactly, but for the first time in two days he didn't feel the oppressing helplessness at being unable to do anything pressing down on him.

"There is something you can do," Kisuke finally relented. "The other four Great Noble Clans are no doubt interested in our investigations. We need to send a representative around."

He opened his mouth to object that diplomacy really wasn't his strong suit, was Kisuke so tired that he didn't realise who he was asking?

"Also, Isshin wanted to know how you're doing." Kisuke eyed him, as though knowing exactly what he was thinking and replying yes, the blond did know what he was doing, thank you for the insult. "You may also want to drop by the Hoshino family compound to reassure your friend and speak to his father, the captain of the Nakatomi's guard retinue."

Well. That changed matters. He should have known Kisuke always had an ulterior motive or several.

"No one but Tessai and Isshin knows that you had been injured. Keep it that way." With that parting shot, the privacy ward lifted noiselessly and the blond disappeared the way he had entered.

Author's Note: No, this isn't the first butterfly. It's just the first that they managed to pin down.

Undergoing rewrite on AO3 (link in profile).

Stop asking me when the next update is.