Chapter Summary: Even after watching for so long, Sasuke is amazed by the whole process. He has never had occasion or interest to watch the medic ninja treat the wounded or ill, at least not with such a procedure.

Chapter Beta: None beyond my own two eyes and editing software at the moment.

Author's Note: I am not a doctor, I know nothing about biology, everything I know comes from Grey's Anatomy and a copious amount of internet research. So anything that doesn't make sense…it's ninja magic, okay? Also, a reminder that the abilities in this fic are not perfectly compliant with canon abilities and possibly don't follow the same logic. It's an AU, I claim creative license :P

戦国時代

Everyone follows Sakura into the cloth enclosure she has set up, Sasuke sees that several wards have been drawn on the ground in a circle. The symbols resemble chakra seals, but he has never seen these before.

"It limits the number of foreign germs and bacteria in the clean area," she explains when she perceives his gaze. "Obviously it's not as effective as an actual surgery, but it will have to do tonight." She offers an impish grin. "It's similar to what Mito-sama might have used, so at least we're in keeping with tradition."

"Hopefully not too much in keeping," Tenzō remarks blandly.

Sasuke frowns at him, still not entirely convinced of the importance of his presence here. "Why exactly is he necessary for keeping the jinchūriki safe?"

"You don't have to talk about me like I'm not here," Naruto mutters.

Sasuke shoots him a pointed look. "A demon inside you should make you the least likely person here to come to harm. We're the ones who ought to be worried."

"The Kyūbi that was sealed within me spent its entire existence hated and feared by men, exploited and used for its power," Naruto explains sombrely. "It's taken at least two generations for it to even consider trusting me enough to lend chakra. Even with that being the case, it's sometimes too much for me and I lose control."

"If that should happen, Yamato-taichō will stop it," Sakura concludes.

Sasuke narrows his eyes. "And does this loss of control happen often?"

"Not as much as when I was a kid," Naruto says with a small chuckle, rubbing the back of his head ruefully.

Itachi and Sasuke exchange wary glances. Sakura notes this, and scoffs. "It doesn't matter. Naruto is only insurance—I'm the one expending chakra here, not him. You were worried about the safety of this, and I've provided at least two fail safes. If that doesn't make you worry less, there's not point to us being here tonight."

A challenge rings in her words.

"You're right, Sakura-san," Itachi says, tone coolly polite in the presence of others. "We have already risked much to meet tonight, it would be a pointless exercise if we didn't continue with it."

She bows her head, then raises an eyebrow at Sasuke, as if to ask if he's satisfied. He nods.

Apparently validated, Sakura brusquely orders Itachi and Sasuke to disrobe and lie on the pallets that she has prepared for them. While they do that, she tells the woman—Ayame, Sasuke recalls—to fetch her several buckets of water and her father Teuchi to stoke up the fire.

"This is a minimally invasive procedure, but we are disposing of deadened cells. They must be destroyed as soon as I extract them," Sakura explains to them. "I'll do my best not to come in direct contact with any genetic material. If I'm unable to avoid it, though, may I have your permission to handle your blood?"

"We would not be here if you did not already have that permission," Itachi informs her quietly.

"Thank you."

From a small kit of medical instruments nearby, Sakura brings out a tiny pouch of earth coloured capsules and removes two. She hands them to Sasuke.

"These are stimulants," she explains to him. "They will increase the amount of blood in your system—and thus bone marrow. The more we have, the easier it will be to extract." Sasuke tosses them back, swallowing them dry, but still winces at the taste that hits the back of his tongue. "You need to lie still now. Your blood cells will multiply and get thicker, which will cause some side-effects—dizziness, headache, shortness of breath…it's all normal. But if you notice anything like that, you have to tell me. All right?"

Sasuke nods.

"Don't just agree and decide to tough it out," she warns him. "Thick blood has the potential to cause a stroke. You are not to die under my care, do you hear me?"

"Heh, she knows you all right," Naruto sniggers, and then gives a sharp cry when Sakura reaches out and smacks him. "Hey!"

"You antagonising him will not help!" she snaps. "Make yourself useful! You and Yamato-taishō are to keep an eye out for any sign that things aren't going well, understand?"

"Understood," Naruto gulps, as she turns to Kakashi.

"And you…you weren't expected, but you can still be of use," she informs him. "I assume you have some medical training, yes?"

"Enough to handle trauma in the field," Kakashi allows; Sasuke suspects it's impossible to be such close friends to Rin and not pick up a few skills.

"Skills like what? Stitching up wounds with twine or putting in a catheter?" she challenges.

"Either, if I have to."

"Good. Then wash up and be ready to assist me if I need another pair of hands," she tells him, reaching for the two large buckets that Ayame brings her. One is filled to the brim with water while the other is empty. Settling down between her two patients, Sakura leans over to meet Itachi's gaze. "I'm going to begin to process to extract all the unhealthy bone marrow in your body. This is a long procedure, and excrucaitingly painful. I will have to put you to sleep."

"No," Itachi says right away, earning a glare.

"I don't have time for stubborn Uchiha men," she snaps. "I'm a healer, not a torturer. You cannot be screaming during this procedure—and yes, you will scream, I don't care how much of a legendary of a warrior you are." She extracts a tiny vial from her hip-pack. "This will knock you out for the next eight hours and you will take it right now."

Itachi scowls, but does as he is told. Sasuke can't help being a little amused at the sight of his brother being bossed around by the tiny medic.

"You're not used to people saying 'no' to you, are you?" Itachi mutters as his eyelids flutter shut, and he goes still on his pallet.

"You'll thank me for that," Sakura tells the unconscious man, a grim smile on her face. She explains to Sasuke, "It's not just the pain of the extraction I'm hoping to spare him. I have to keep any healing to a minimum during the procedure."

"Why?"

"Medical ninjutsu mostly involves regenerating cells," Kakashi interjects. "If you regenerate the same cells you just got rid of, you'll be here forever."

Sakura nods. "And the longer we have to repeat the process, the more likely it is we could trigger shock or sepsis."

"And if that happens?" Sasuke challenges.

"Then we treat him—minimally—and start over from whatever stage of the process we're in," Sakura says. "It's not ideal…but it's all we can do with what we have."

Everyone is silent, and the atmosphere of the room is heavy with tension.

"This is your last opportunity to stop this," she goes on seriously. "Once I start…I won't be able to stop without seriously compromising his health."

Sasuke turns his head to study his brother's face, peaceful in his unconsciousness. He wants to see that untroubled expression for many years yet.

"Begin," he tells her.

戦国時代

Time passes, although Sasuke isn't entirely sure of how much. The symptoms Sakura warned him about—dizziness and a pounding headache—make thinking a chore. All he can do is watch as she works on his brother, her face set in a permanent frown of effort.

There is a seal drawn on Itachi's chest, right across his sternum, and encircled by similar warding characters to those which surround the two pallets. They gleam occasionally in the firelight, with the same blue-green shine of Sakura's chakra, no doubt fighting off foreign bodies as she works. Even after watching for so long, Sasuke is amazed by the whole process. He has never had occasion or interest to witness a medic ninja treat the wounded or ill, at least not with such a procedure.

After placing her hand in the bucket, Sakura draws together a ball of water and then presses it into Itachi's body; though he is unconscious, his frame jerks when she does this. She concentrates for several minutes and then draws the globule back out of his skin. In it, Sasuke sees a blackish-purple sludge.

"All of that should be bright red," she remarked the first time she did this, and Sasuke felt sick.

That was all inside Itachi? No wonder he has been so ill.

The waste is thrown into a wooden container which Teuchi tosses in the fire at once. Yamato uses his wood mastery to provide another container for the next handful of blackened blood that Sakura pulls from Itachi's body.

With every extraction, his skin changes from pale and smooth to mottled and bruised.

As the hours tick by, Naruto and Yamato sit by in edgy silence; Naruto appears to be focussing on something while Yamato observes him warily. Sakura occasionally pauses and inspects her patients' vitals. She asks about Sasuke's symptoms, while Kakashi measures Itachi's pulse. Sometimes she frowns and uses a tiny amount of healing chakra on one area of his body or another. Each time she does, Sasuke knows that time will be added to the already lengthy procedure. Sweat gathers on Sakura's brow, mopped by Ayame when she comes by with refilled buckets of water, and twice she lists forward, only to be caught by Kakashi.

"You should take a break," the older man suggests. "Even just a minute or two might make a difference."

"A minute or two could kill me patient."

"If you pass out, he'll die anyway."

"I'm not going to pass out, it was just a dizzy spell," she snaps in irritation. "That happens when you concentrate your chakra for such a long period. This is usually a simple poison-extraction technique—it rarely exceeds half an hour. But I'm not extracting a foreign material, I'm extracting his own cells, which by their nature want to stay there. So stop talking and let me concentrate!"

But in spite of her severe words, Sasuke notices that she seems paler, and there's a worried crease in her forehead.

"Sakura…you've extracted what appears to be the entirety of his blood supply," Kakashi whispers. "His heart won't keep beating at this rate."

"I know."

"Then how are you going to…?"

He trails off as the seal on Sakura's forehead glows, and the black, ribbon-like markings snake across her face and down her arms. Sasuke stares in amazement as she presses her left hand flat against Itachi's chest and the mark stretches beyond her skin onto his brother's. The bands crisscross over his body, disappearing beneath his hair and clothing, and in his sleep, Itachi's face contorts in discomfort.

"What the hell are you doing?" Naruto demands, entire frame going tense. "Chakra's not a permanent replacement for blood! You'll burn up if you do that!"

"That's why you're here, remember?" Sakura bites out, eyes focussed on her task; with her right hand, she continues to draw out the deadened cells even as she feeds her own chakra into Itachi's body.

"But Sakura—"

"If you see me falter, help me, otherwise stop distracting me."

Naruto's fists clench, and Sasuke wants to argue as well, but his tongue is heavy in his mouth and his vision continues to swim. Kakashi continues to look wary, standing nearby in case she falters once more.

The seconds tick by in sync with the beat of Sasuke's heart, and Sakura's breathing becomes irregular. When blood suddenly leaks from her nose and the black ribbons encircling Itachi's body begin to recede, Naruto swears and snaps a hand out. As he grasps her shoulder, there's a sudden flare of chakra, so strong that Sasuke's stomach clenches; he's not a sensor-type, but he can sense the blistering warmth from it as if he was just set alight. Sakura is surrounded by a bubbling, red film of energy, and the mark connecting her to Itachi strengthens again.

"Thanks," she says through gritted teeth, still digging dead cells out of him. "I'm almost…finished…"

"Sakura…" Sasuke attempts, but his words are slurred.

Her eyes flit briefly to him and then back to her work. "Naruto, cover him as well. I don't want him succumbing to a blood clot while I can't help him."

"Right," the blond man says and leans over, pressing his hand to Sasuke's shoulder as well.

If before he felt as if he was set on fire, now he wonders if he wasn't catapulted into the sun. It is as if every nerve and synapse in his body has suddenly connected, and in his confusion, he imagines he hears a stranger's voice. Low, deep and ancient, whispering to him.

'...I am the one who will establish peace and order…two clans…two bloodlines…'

"Kakashi," Sakura commands, bringing him forcibly back to the present, "connect the intravenous catheters now." Her hand is still pressed to Itachi's sternum, but now her other one rests on Sasuke's as well. "Radial artery in Sasuke's wrist to median basilic in Itachi's elbow—do you need me to show you that?"

"No, I've got it," he says, and Sasuke experience a tiny needle prick in his left wrist. "What else?"

"That's it. I'll need to stimulate blood flow myself," she says. "It's a tricky process—we don't want any air bubbles or other obstructions passed between patients."

"That's it? It's just a transfusion?"

"The marrow cells will automatically know where to go," she agrees. "The process usually takes two weeks to a month, but I will speed it up. His system will be as good as new in a few days as long as he rests. He might be weaker for longer though…"

She attempts a confident smile, but it doesn't stay very long, and then she glances down at Sasuke. "How are you doing?"

"Fine," he bites out, trying to ignore the ringing in his ears.

"You'll feel better in a few minutes. Sort of. There will be some more disorientation as the excess blood in your system will be evacuated rather quickly. But don't worry, I'm protecting your heart from damaging itself."

"Are you?" he asks dazedly.

She gives him a look he can't interpret, and then closes her eyes, frowning in concentration. Slowly, he notices a draining sensation, his stomach fluttering as if he is being spun about, and a severe sense of vertigo. Out of the corner of his eye, he watches the trail of his own blood inch through the small tube attached to his brother.

This time he is more aware of the slow crawl of time and knows that still more hours have passed. Sakura's entire form is shaking beneath the red cloak of chakra, and Naruto sits cross-legged beside her, face scrunched up in concentration.

Eventually, Sakura removes her hand from Sasuke, along with the tube connecting him to his brother.

"Your part in this is over," she tells him. "Now I simply have to force the cells in Itachi's body to replicate. I'll use mine and Naruto's chakra to cloak the new cells so his body won't attack them. We'll see if it works soon enough."

"Do you need to rest first?" he asks before he can stop himself.

"If I rest now, I may sleep for the next few days," she tells him, absently brushing his sweat-soaked bangs from his face. Sasuke is distantly aware of two sharp, surprised intakes of breath from Yamato and Naruto, but those pale in importance next to the tiny smile she gives him.

Well, if they didn't know before…

Sensing that the procedure has come to the most difficult juncture, everyone in the room goes utterly quiet, watching as Sakura works. She makes several hand signs with her free hand, then presses it to Itachi's chest; a beat later, she uses both hands to shove a generous amount of chakra into him. Itachi's body arches upward, as if it has been hit by a bolt of electricity, and then—

The red cloak around Sakura disappears, and with it her healing mark.

"Naruto," she prompts, a warning in her voice, but when she glances up again annoyance gives way to concern. "No."

Sasuke follows her gaze and sees that the blond man is unnaturally tense, his hands gripping his knee so tightly that they appear to have punctured skin. Which should not be possible—except when Sasuke looks closer, he sees that Naruto's fingers now have claws.

"What the hell is going on?" he demands, stumbling to his feet; the room spins, reminding that he doesn't have enough blood in his system to be of much use.

"I can't…I'm losing…!" Naruto begins through gritted teeth and does Sasuke imagine it or are they getting longer?

Blue eyes flicker in the dim light, turning into red slits, and Yamato's hands are already forming a seal.

Sasuke tries to put himself between Sakura, Itachi and Naruto, but his limbs falter as if they are made of lead. He is nowhere near in the condition to physically counter…whatever is happening to his erstwhile rival. The other man's chakra seems to surround him, splitting into nine shapes—like tails.

"Naruto, hold on—" Yamato starts, and several wooden branches burst through the surrounding ground, headed straight for Naruto.

Before he can complete it, a tail-like chakra appendage whips out and tosses the man across the room. There's a brutal thunk of skull meeting stone, and he slumps into unconsciousness. As Kakashi moves to stop it as well, it another tail snaps out headed for him.

"Get…Ayame and Teuchi…out of here!" Naruto growls, saliva and blood leaking from his clenched teeth. "And…Sakura…!"

Kakashi is already shoving the two civilians out of the way as another tail launches itself at Sakura. She throws up her right arm to block it, even as her left continues to press against Itachi. There is the smell of sizzling flesh, as if the touch of Naruto's chakra is too hot for human skin.

"Naruto, fight it!" she cries, eyes wide as she surveys what's happening to Naruto but still leaning protectively closer to Itachi's body. Sasuke instinctively knows that she won't leave her patient no matter what happens.

But Naruto is stalking forward, eyes darkening even as he tries to hold himself back, and Sasuke's body moves without thinking. He throws himself into the other man's path, weaponless but for his Sharingan spinning to the surface.

His brother's words echo in time with his heartbeat.

They say he could command untamed demons with his eyes.

"Don't," he commands, both his rival and the beast within him.

The small hut fades around them, as if cloaked in a genjutsu, and Sasuke stands before a cage, a snarling, bubbling creature before him. The raging ball of negative energy and dark intent appears to be approaching Naruto, but upon seeing Sasuke is rumbles in contempt.

"Ah, so you're the latest Uchiha," it sneers. "Allow me to congratulate you on making it this far."

"Why are you here?" Naruto demands, looking panicked. "You should protect the others!"

"Sakura can handle herself," Sasuke replies, hoping his sounds more confident than he feels. He stares up at the enormous fox demon. "I see. So, this was your secret power this whole time. Hard to believe that something like this exists inside you."

"Impressive that you've become able to see me here within Naruto," the fox rumbles. "Such would be the power of that accursed Sharingan…and your forsaken ancestry."

"That's right," Sasuke realises, "You've seen eyes like these before."

"I have seen it all before," the fox sneers. "You are not unlike a certain Uchiha Madara." It laughs coldly. "Surely you know of his fate?"

Sasuke narrows his eyes and shoves his hand forward, grabbing the fox by his nose.

"I am not Madara," he tells it, and wills as much of his own chakra forward to dispel the spirit.

"And yet…like him…you can suppress my power," the beast muses in what appears to be its parting shot. "I wonder what else you have in common with him."

It's dark laughter fades, and the world spins until they are standing once more in the hut.

Naruto falls to his knees, features twisted into astonishment as he gazes up at Sasuke, who barely spares him more than a cursory glance.

Kakashi has returned, erecting a mud wall between Naruto and Sasuke, and the rest of the occupants. Sakura is still leaning over Itachi, face bone pale, and her arm bubbling with a blistering rash, while Yamato rubs at the back of his head.

Satisfied that everyone has survived, Sasuke finally returns his attention to Naruto. He shoots him a glare.

"Sometimes it's too much for you?"

つづく

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クリ