Author's note, summer 2016: After letting it collect dust for a decade, Marrow deserved a bit of love. It has been rewritten almost entirely – and also, updated. I am much happier with it now, flaws and all.

Marrow is an AU fic that diverges from the manga from around the Kimimaro/Gaara battle onwards: Orochimaru has Kabuto keep Kimimaro alive as he is unwilling to lose such a bloodline limit. Years later, Sakura is abducted by the Sound while on a mission to Sand. She receives the following proposition: heal Kimimaro in exchange for the guarantee that Orochimaru will not use Sasuke as his next vessel.

For those of you who don't remember him, Kimimaro is the pretty one who uses his bones as weapons, fighting off first Naruto, then Lee, then Gaara, all while suffering a terminal illness. He was slated as Orochimaru's next vessel. There are not enough fics about this guy. (Possibly because he's, uh, dead, but still.)

Kimimaro is three years older than Sakura, making him 23 here.

Cover art: commissioned from Akemiin and used with permission.

VVV

"In the end, it will only be to your advantage to aid us as best you can, Sakura Haruno."

In the gloom of the dark room, Sakura could barely make out Orochimaru's pale face. Though her heart raced, she didn't feel the cold, paralyzing fear that she had felt when she had first met Orochimaru on that fateful day, so long ago now, in the Forest of Death. That fear had matured into a visceral sense of dread and loathing, because now she knew this man – she knew what he had done, and what he was capable of.

Sakura felt the bile rise in her throat when Orochimaru's abnormally long tongue slipped out to moisten his thin lips.

"What is your choice?"

Sakura took a breath before she answered, trying to keep the quaver in her voice to a minimum.

"Help you, or death," she said with much more boldness than she felt. "A fine choice."

Orochimaru's smile widened – he was amused, perhaps, by her bravado. Behind him, a shadowy figure shifted and Sakura was reminded that that traitorous bastard Kabuto was here too.

"Go over the terms of this proposition of yours," said Sakura.

Orochimaru stared at her.

"…Please," added Sakura softly.

An almost imperceptible nod on Orochimaru's part confirmed that Sakura had done the right thing by adding that please, because this man had a strange regard for politeness, custom and respect, even if he was cruel and crazy…

"Of course," said Orochimaru with a voice of silk and venom. "It is a simple proposition. You are the only medic-nin alive who could possibly heal Kimimaro. News of your exploits has reached us in Otogakure. I am informed that your creativity in the field means you surpass dear Tsunade in many ways… and even Kabuto, who is himself something of a prodigy at medical ninjutsu, was highly impressed by your file."

Orochimaru gave a kind of half-shrug, one which set his dead arms swaying momentarily. "However… Kimimaro's condition continues to defy Kabuto's abilities."

Sakura saw the shadowy figure behind Orochimaru look at the floor.

"So our hopes lie in you and your skills," continued Orochimaru. "It is a rare condition, you understand. Rare and, apparently, untreatable. It has proven to be quite stubborn."

Sakura looked up at him, full of curiosity in spite of herself: she had never encountered anything truly untreatable before.

"However. I have heard that you are stubborn too, and have pulled off no less than medical miracles in Konoha. So here is my proposal. If you manage to heal Kimimaro fully, I will proceed with my original plan; that is, to take Kimimaro as my next vessel."

"And Sasuke?" said Sakura.

"And your little Sasuke-kun will go free."

"I'm – I'm not sure that I can believe you," said Sakura, possibly making the understatement of her life, but not daring to be any more accusatory.

Orochimaru studied her with those slitted golden eyes.

"Tread carefully," he said in a voice that was both soft and full of warning. "You might offend me by suggesting that I am not a man of my word. You do not want to offend me, Sakura."

Sakura blinked and looked away, her heart in her throat. The man could radiate death intent like no other shinobi she had ever encountered.

"I will not take Sasuke as my next vessel," repeated Orochimaru. "You have my word."

Sakura took a moment to parse this last sentence, because he had worded it quite carefully. "And the vessel after that?"

There was a brief pause.

"That would be in a few years," said Orochimaru. "We'll consider that question when the time comes."

"I want a guarantee that you will not take Sasuke as a vessel at all," said Sakura. "Not just temporarily."

"I cannot do that."

"Then I refuse."

"Then you will die."

Sakura had been on the receiving end of death threats more times than she could count. But this statement of Orochimaru's was different – it wasn't even a threat, just a fact. There was such certainty to it, such casual finality, because he was powerful enough to end her life now, if he so chose…

She swallowed hard.

"If you kill me, Kimimaro will never be healed."

"I know this," said Orochimaru. "That is why you are still alive."

"How long will he last, as a vessel?"

"Three years," said Orochimaru with a shrug that set his lifeless arms swinging. "Perhaps four."

"And during that time, Sasuke will be free?"

"Yes," said Orochimaru.

"What about the seal?" asked Sakura, suddenly remembering the hideous mark and its effects on Sasuke's body and mind.

"The seal…" Orochimaru tilted his head and considered her. Again that unnatural tongue flicked out. "The seal stays."

"But –"

"I will not be making concessions on that front," said Orochimaru.

Sakura resisted the urge to shoot him a glare because, truth be told, Orochimaru hadn't been making any concessions whatsoever. This wasn't so much a negotiation as an information session for Sakura – here's what you do, or you die.

"Sasuke won't be free," said Sakura. "Not truly. Not with that seal."

"He will be free to go as he pleases and do as he wills, and his body will remain his for the next few years," said Orochimaru. "Really, girl – isn't that better than the alternative?"

It was, but it didn't make Sakura any more comfortable. She bit her lip as she mulled the arrangement over.

"I want to speak to Sasuke," said Sakura.

Something that very much looked like irritation flashed across Orochimaru's pale face, but it disappeared just as quickly. "That is… not possible at the moment."

Sakura looked up sharply. "Why?"

"Because we do not know where he is."

Sakura studied Orochimaru and decided to believe him, because that rapidly-quelled flare of irritation seemed very real.

"I see," said Sakura. "And… what happens if I fail to heal Kimimaro?"

"That would be an unfortunate outcome," said Orochimaru. "You would be – disposed of."

"And Sasuke would be used as your vessel."

"Precisely."

Sakura bit her lip. She really didn't like this so-called deal, but she liked the prospect of imminent death even less. "How long do I have to work on Kimimaro?"

For the first time since Sakura's audience with Orochimaru began, Kabuto spoke up.

"If I may…" said Kabuto, pushing up his glasses. "By my analysis, he has three or four months left. I've been able to slow his deterioration over the years, but not stop it. He'll be dead within half a year."

"I see," said Sakura. "And if I heal him successfully, will I be allowed to leave freely?"

"Of course," said Orochimaru.

Sakura could not hide the scepticism that coloured her gaze. Orochimaru's eyebrows contracted minutely when he noticed, so she headed off his annoyance with another inquiry before he decided to off her for questioning his word again.

"Will I have all the equipment necessary for potentially complex medical procedures?"

"Kabuto's laboratory is well supplied. He has also written extensive notes on the subject of Kimimaro's condition, which he will provide to you."

Sakura rubbed a finger along the bridge of her nose. With the proper materials, she was certain she could heal anything. Hopefully.

"Alright," said Sakura. "I accept to heal Kimimaro so that he is used as your next vessel instead of Sasuke, and so that I will be freed."

"Smart girl," said Orochimaru.

Sakura was repulsed to see his endless tongue exit his mouth and wrap around his right elbow. He lifted his dead arm towards her in a gesture that was a mockery of a handshake. Sakura hesitated, then took the proffered hand. It was cold, clammy and soft – a cadaver's handshake. She released it quickly.

"I am quite pleased that we were able to come to such a cordial agreement," said Orochimaru. "Kabuto will show you to your rooms, the laboratory, and the patient's ward."

Sakura nodded stiffly. She found herself shaking from a slight adrenaline-fueled tremor, now that the threat of immediate death had been lifted.

"And before you go," said Orochimaru. "I would have you know that escape attempts would be… unwise. We are more than equipped to detect those here, you see, and it would go badly for you if you were to try."

"I understand."

"I am also forbidding you from attempting to communicate with the world beyond the Sound. You understand, of course. I cannot have a retrieval squad knocking at my door, it would put a – a slight damper on my plans."

Sakura blinked at him, because thoughts of sending a message had, of course, crossed her mind.

"Yes," said Sakura.

"Excellent," said Orochimaru. "We should get along marvellously. Kabuto – would you show Sakura to her rooms?"

Feeling more than slightly ill, Sakura followed Kabuto out of the audience chamber.

VVV

Sakura walked behind Kabuto in nervous silence as they made their way down endless wood-panelled corridors lit only by flickering torches. Each new turn brought them to a corridor so perfectly identical to the last that Sakura's mental map quickly became a useless jumble of crisscrossing passageways. Her sense of direction told her that they weren't going in circles, but her eyes did, and Sakura began to suspect that some crafty genjutsu was at work.

"Here we are," said Kabuto, gesturing to a door nestled into the woodwork.

Sakura followed him into the room. Like the remainder of Orochimaru's complex, it featured those intricately carved wooden walls; however, the flickering torches were superseded here by a single electric bulb hanging from the ceiling. The room was sparsely furnished: a cot occupied the bulk of the space, a rickety desk stacked with a few writing implements crouched in the corner, and a folding chair leaned against the wall.

Sakura glanced into the even more modest bathroom, with its small shower, sink, and threadbare towel hanging by a nail.

"Acceptable?" asked Kabuto.

"Yes," said Sakura, aware that anything she said would be reported back to Orochimaru and therefore not daring to complain about the accommodations.

"I had your things brought in," said Kabuto, showing Sakura where her bag was tucked into a corner. "Everything that was there when we – ah – found you, is still there, minus the weapons and scrolls, for obvious reasons…"

Sakura quelled the flare of irritation that blazed at the thought of any Sound nin pawing through her possessions.

Kabuto noticed. He turned to look at her and surprised her by looking apologetic. "You understand."

The look was unexpected and Sakura was reminded of the long-ago days when she considered Kabuto a friend and ally. It was difficult to reconcile that Kabuto with this one, the one who was the right-hand man to an immortality-obsessed villain, and who, it was rumoured, conducted inhuman experiments on very human subjects…

"Of course," said Sakura. She nodded towards a door near the head of the cot. "What's through there?"

"Ah," said Kabuto, making his way there. "This way to the ward."

"The ward?" repeated Sakura. She followed him through and was surprised to find that the door did indeed lead to a dim room glowing with the flickering lights of medical equipment.

The layout struck Sakura as highly unusual. "Have you been planning this long?"

"When we first heard of you, it crossed our minds that such an arrangement might be favorable, yes," said Kabuto. "Orochimaru excels at long term planning. Very long term…"

"I see," said Sakura. She suppressed the urge to shudder, understanding from reading between Kabuto's lines that she had been identified for this role a long time ago, and had probably been under surveillance for just as long, with her every move watched until they found a suitable moment to abduct her.

Kabuto lead Sakura into the dim sick room, where she had her first glance at her patient: she could make out the figure of an unmoving man on the bed, so still and thin that he might have been a corpse with a white sheet for a shroud, until she heard him take a slow, laborious breath.

"Lights seem to irritate him," said Kabuto. "We keep them to a minimum. Follow me through here."

"Is he conscious?" asked Sakura, glancing back at the figure.

"Rarely."

They passed through the ward into the laboratory on the other side. Kabuto closed the door behind them with a snap and switched on the light, flooding the laboratory with sterile white light.

As he walked Sakura through his materials and equipment, she found herself impressed at the operation that he had managed to set up in such a place. There was equipment here that she didn't even have access to at the Konoha General.

"And here," said Kabuto, pointing to a bookcase filled with binders and notebooks, "are all of my observations until this point. Some of these date back several years, when his illness first began to manifest itself. They are arranged in chronological order."

Kabuto pointed to some thick notebooks stacked onto a side table. "And these are more geared towards Kimimaro's personal history, his clan's medical history, and his bloodline limit and abilities as far as we know them."

"This is going to be very useful," said Sakura.

"Yes. Orochimaru decided that it would be best for you to have all the information that we could provide."

Sakura ran her fingertips along the spines of the dozens of brimming binders on the shelves, wondering how many of these she could get through a day.

Kabuto's voice interrupted her musings: "I will be holding… other duties while you fulfill this post."

"Oh?"

"Otogakure stuff," said Kabuto vaguely, pushing his glasses up with a knuckle. "I'll come and check on you and Kimimaro as often as I can."

"I'm going to be left alone with Orochimaru's prized vessel?" asked Sakura, surprised. "With no supervision?"

Kabuto studied her with his dark, intelligent eyes. "Those are my orders."

Seeing that Sakura's expression of mingled confusion and suspicion persisted, he continued: "Orochimaru has a high opinion of your integrity, you know. He says that Tsunade would never have made you her protégé if you didn't have – how did he put it? Oh yes – insufferable amounts of moral rectitude. I think he trusts that you're too principled to do anything you shouldn't. Like kill a half-dead man."

Kabuto gave Sakura a quick grin. For her part, Sakura wasn't sure whether or not to be flattered by this mostly-complimentary assessment, given its dubious provenance.

"And, of course," continued Kabuto, "if Kimimaro dies – or is killed – your life is forfeit. And Sasuke becomes the next vessel. I think that you have the right – ah, motivation – to do the right thing here."

"I see," said Sakura.

Kabuto studied her over his glasses for a moment. "So you're the medical lead on Kimimaro as of now. You can monitor and examine him at any time, and I'll answer any questions you have about him to the best of my ability. However, you are not to undertake any invasive surgery or the like without coming to me first."

"I understand."

"I've been asked to take care of his food and hygiene needs, since those are tasks below the level of a medic-nin of your calibre."

Sakura raised her eyebrows. "You're hardly a junior nurse yourself, Kabuto."

Kabuto looked appreciative of the compliment, but nevertheless shook his head. "Orders are orders."

He led her back into the ward and paused for a moment in front of Kimimaro's bed.

"This is new for me, you know," said Kabuto. "I'm really not used to failing Orochimaru."

"You haven't failed," said Sakura, coming to a halt next to him. "If you had, Kimimaro wouldn't be alive."

"Still," said Kabuto, looking at the unmoving figure. His gaze hardened, as though the sick man was personally responsible for his failure.

After a pause that grew long enough for Sakura to become uncomfortable, they proceeded back to her room.

"I'm impressed by you, you know," said Kabuto. "You shouldn't even be standing right now, not with that dose of sedatives that we administered…"

Sakura shrugged noncommittally. "I can take care of myself."

"I can see that," said Kabuto. "Anyway – I guess you might take it amiss if I said to make yourself at home here, since you're not exactly here willingly… but I hope you'll find it comfortable enough. You'll get three square meals a day and I'm to offer you access to one of the courtyards if you behave yourself."

Sakura nodded, deciding that compliance was the best course of action for the moment.

"Okay," said Kabuto. "I'll be in touch. I'm locking this door – and yes, I know that you could smash it off of its hinges if you wanted to. So I'm warning you now that it's rigged with a barrier jutsu and an alarm jutsu."

"Duly noted," said Sakura, privately grateful for that extra bit of intel.

Kabuto gave her a polite little smile and closed the door. She heard the lock turn a moment later and then felt a minute flash of chakra as the jutsus were set.

VVV

With Kabuto gone, Sakura collapsed onto the cot and stared at the carved ceiling. She laid there for a long time, trying to make sense of the last 72 hours of her life. Hours which had been utter insanity – her return to Konoha from Suna was interrupted by a violent abduction, she was drugged, she was transported to a Sound base in an unknown location, and, just now, she had made a deal with the devil to save her childhood crush's life…

This last thought was what pulled Sakura out of her whirling confusion of memories and back to the present. She sat up and pressed her fingertips to her temples, deep in thought. Her options at this point were clear. Option one was blowing this popsicle stand. Sakura knew that she was bright and she had no doubt that she could, with careful planning, come up with a practicable escape plan. If successful, she could get back to Konoha and redouble her efforts to find Sasuke and warn him away from Orochimaru – but she, and the Leaf village's forces, had been trying to do that for years, and failed utterly.

This option presented high risks and failure would endanger both herself and Sasuke. And Orochimaru was a goddamn genius – could she really eclipse his escape prevention measures, in his very own compound? Sakura bit her lip in a moment of self-doubt. Her other worry was that Orochimaru did actually have a sense of where Sasuke was and would be able to get to him and use him as a vessel before Sakura could reach him, if she broke the terms of their bargain and made a break for it.

So, option two. The alternative was to abide by her deal with Orochimaru, at least for now. It was the lower-risk option, as far as Sakura could see: there was no escape attempt to botch up and subsequently get killed for, and, looking into the medium-term, Sakura knew that her life was more or less safe as long as she was useful to Orochimaru; that is, as long as this guy Kimimaro was being healed.

And most of all, adhering to the terms of the deal would buy Sakura time. Time for her to come up with some other more viable plan, perhaps – but more importantly, time for her disappearance to be noticed by the Leaf. Because when the Fifth realized that Sakura had been kidnapped, she would move heaven and earth to get her back.

Knowing her mentor's thunderous temper as she did, Sakura suspected that Tsunade might just eradicate Otogakure out of fury at Orochimaru's audacity in abducting Konoha's most cherished kunoichi for his own purposes.

Sakura drifted into a beautiful daydream of Tsunade bulldozing through the Sound's walls with her Strength of a Hundred Seal released, of Naruto and Kakashi flying in behind her with jutsus of wind and lighting ablaze in their fists, of Konoha's famed shinobi launching in after them, of Orochimaru and Kabuto receiving a massive and well-deserved beat-down…

Yes. Overall, option two was the more practicable one right now, and not only because she wanted to see that beat-down. She wouldn't risk a failed escape attempt and Orochimaru's subsequent wrath, she would guarantee herself some security by working on Kimimaro and keeping herself valuable in the snake-sannin's eyes, and she would give Tsunade time to put together a retrieval team.

Sakura therefore turned her attention to the task at hand. For the next few weeks, these three rooms – her quarters, the ward, and the laboratory – were her domain. Goal: heal the Sound nin in the next room and get the hell out of here alive.

Sakura's first instinct when faced with a problem was hitting the books – and so she made her way to the laboratory, where she stacked up a first series of binders. Glancing at her watch – it was 7:00 p.m. – Sakura figured on about six hours' worth of learning before sleep claimed her. She was far too wound up to try to rest right now anyway; adrenaline lingered in her system and her chakra was still fighting the effects of whatever drug Kabuto had hit her with to knock her out.

As Sakura passed through the ward on her way back to her room, hefting the notes, the sound of Kimimaro's strained breathing caused her to slow her steps. Now that she was alone, the sound disturbed her. This shinobi had been reported dead years ago…

Suppressing a shudder, Sakura slipped into her own room and shut the door, having decided not to undertake any physical examinations of the man before she knew exactly what she was dealing with.

The next few hours passed in a blur of information absorption. Sakura began with a review of this Kimimaro Kaguya guy's personal history, expecting a more-or-less generic biography with a few tragedies thrown in, as in the life of any young shinobi. Instead, she found herself reading a tale of such vicious abuse and hardship that it made her wonder what kind of man – or monster – was slowly dying in the next room.

Though Kabuto's record was written with the objective, clinical coldness typical of those in the medical field, Sakura felt a twinge of empathy while reading about Kimimaro's childhood, which had apparently passed in a horrific sequence of violence, imprisonment, and more violence. She learned that, as a child, he had been used as a weapon by his clan – unleashed on enemies when his powers were required, but otherwise kept caged with minimal human contact in deplorable conditions.

It had altogether been a very sad existence. Kabuto's notes indicated that Orochimaru had first encountered Kimimaro at around age 13, befriended him, and eventually discovered that Kimimaro was powerful enough to make a very desirable vessel. It was at that point that Orochimaru had bestowed (Sakura wrinkled her nose at Kabuto's word choice) the cursed earth seal upon Kimimaro. And then Kimimaro had begun to manifest the beginnings of the illness that now threatened his life…

Sakura closed the binder and passed a hand over her face; she had not expected quite such heavy reading… nor had she expected to feel this nascent sense of pity for the enemy ninja in the next room.

Hoping for something lighter, she reached for the next file, which was dedicated to Kimimaro's bloodline limit.

"Shikotsumyaku – Dead Bone Pulse," whispered Sakura, rolling the unfamiliar, and slightly morbid, word on her tongue.

Sakura fairly devoured Kabuto's notes on Kimimaro's bloodline limit; the ability to manipulate one's entire skeleton was absolutely fascinating to her from a professional standpoint. She learned that, as the last living descendent of the Kaguya clan, Kimimaro was the only remaining living practitioner of the Shikotsumyaku. From a medical and biological perspective, he was therefore a priceless rarity, even moreso, as Kabuto pointed out in a scrawled sidebar note, than the Uchiha clan, who at least had two living males to carry on the bloodline.

A detailed analysis of Kimimaro's attacks and defenses followed, which, Sakura thought ruefully, would have been tremendously useful to Naruto, Lee and Gaara when they had fought the guy so many years ago. Her attention was riveted by Kabuto's description of one of Kimimaro's special weapons, his spinal whip – how the man continued to function, much less fight, when his spine was in his hand was beyond Sakura's imagination. Kimimaro was also listed as a taijutsu prodigy and master swordsman. Sakura skimmed through the paragraphs about his clan's traditional sword dances with their unexpectedly pretty names – the dance of the larch, the dance of the pines, the dance of the camellia, the dance of the seedling fern…

Kimimaro's healing powers intrigued her. In Kabuto's words, he was a freak of nature – he didn't use chakra to heal, or at least, not consciously. Each time his skin was pierced, whether by one of his own bones or an enemy's blade, he healed almost immediately. He also had the ability to grow a virtually impenetrable defensive bone layer under his skin.

Having reviewed Kimimaro's abilities, Sakura could understand why he was so attractive to Orochimaru as a vessel: Orochimaru was obsessed with regeneration, second skins, cheating death – and even the Sharingan, with all of its advantages, did not confer those powers…

The extreme lengths that Orochimaru had gone to, to keep Kimimaro alive over the years, were also now making sense – devoting untold hours of Kabuto's expertise to him, putting together the well-equipped lab, this whole carefully planned set-up in the Sound base, and Sakura's own abduction…

It was almost counter-intuitive, but this realization was a comfort to Sakura, because it meant that, for now, she was valuable to Orochimaru. Right now, she was in a way a priceless rarity herself; one of the few (if not the only one) who could possibly heal his precious vessel.

Sakura looked up from the notes and took a deep breath.

For now, she was safe.

For the first time in 72 hours, Sakura allowed herself to sit back. She dropped her shoulders and felt some tension ease off as she lost herself in staring at the carved lines in the wall across from her. This was good. This was a positive development. If she did manage to heal Kimimaro, Orochimaru would most certainly be using him as his next vessel, and so Sasuke would be protected for the next few years, which bought her more time to find him and knock some sense into him…

Her eyes dry from too much reading, Sakura washed up and quit for the night, her brain abuzz with new information and just a little glimmer of hope.

VVV