It's very interesting to see all the theories for the mastermind behind Kakashi's poisoning. Some of you were mostly right. But the stage has far more players upon it and they all have their own agenda...

Also, it's worth noting that Boruto Next Gen got thrown out the window the moment this fic started. However, this chapter mentions one thing that makes sense with canon, so I'm keeping it.

Warnings for Kimimaro being a little too into body horror, Danzo being Danzo, and cute chibi-Naruto with Parental!Tenzo(Dadzo? Tendad? Parentenzo!). And Inoichi needs all the aspirin.
Just occurred that...hospital intensive-care patient might be a warning.

Poison: Secrets in Circles

Shisui paled. "It...is possible that Kotoamatsukami might not have gotten everyone; it's not really designed for multiple targets. There's also always the danger of creative interpretation of orders. This isn't a coup after all, not really."

"At the moment," Inoichi added. "Oh, don't get me wrong, I'm still really fucking reeling from the fact that a founding Clan was plotting under our noses. Don't worry, I'll get over it later. But now...we can't be sure that Yashiro Uchiha was working alone, then. And why Kakashi? The Bloodline Theft issue with his Sharingan was settled amicably nearly a decade ago!"

Shisui raised an eyebrow. "You just answered your own question?"

"...Okay, maybe we need to revisit that incident, but still! Why not someone like me? Killing me would, not to toot my own horn or anything, be a major loss in both resources and morale. Kakashi doesn't have much of a social circle, he's spent the last few years in ANBU so it's not like he has any widely-known past missions and for all his power he is just a Jonin with no other responsibilities."

"Except an Apprentice," the Sandaime spoke up from where he had been ruminating in the corner. "This reeks of a distraction, or more likely, obstacle removal. It seems that Kakashi was not meant to survive at all, but he is still out of commission and Konoha is wary."

"Mob mentality," Inoichi grimaced. "Too wary. Keep things tense, scatter a few more terror attacks and we'll have an arena full of feral animals baying for blood. If had been an attack on, say, a public area full of mainly civilians, the Village would be banding together right now. But instead it was an attempted assassination on one of our own."

"The question, Shisui," the Hokage picked up. "Is the purpose of this. If Yashiro was acting alone, was it a last act of rebellion or part of some misguided plan to restore favour to the Uchiha? If there are others like him, the same questions apply, with the caveat of what is their next move? Will they present themselves as saviours in the ensuing confusion? Or, what do they now get out of Kakashi's incapacitation?" He took a quick inhale from his pipe.
"And possibly, someone else wants the Uchiha to take the blame, or otherwise out of the way."

"Yashiro was a staunch supporter of the coup," Shisui noted quietly. "And I'm definitely inclined to believe that he had an accomplice; he worked best in a pack, with backup, if you know what I mean. And, he got out of Konoha with no-one the wiser at all. He is not that good. Or, more likely was. He's evidence now, after all. And it's standard procedure to eliminate such things."

"Then we find the body, or what's left of it." Inoichi was firm. "And it's worse than that. His accomplice has to be someone with high clearance."

Sarutobi extinguished his pipe. "I have posted ANBU I personally trust around Kakashi. Shisui; I trust Itachi will be willing to keep an eye on Kimimaro?"

"They're brothers in all but law and blood these days, and I'm sure Kimimaro will appreciate the help. He's not exactly some helpless child himself, like we tend to forget."

Blood welled around the sharp tooth that had broken the skin and oozed downwards. The slight sting of pain joined the dull throbbing of the other bloody nips as Kimimaro examined intently the scrolls spread out before him.

They had kicked him out of the hospital, citing visiting hours being over as the reason, and he had reluctantly complied. It was, after all, time for research and development.

He had found the most unexpected little gem of a jutsu; the affectionately-named Rubber Stamp jutsu. Originally for espionage, allowing for any script written in ink infused with the caster's blood to be copied exactly, time after time. The Fourth Hokage had used it to covertly mark things and people with the Hiraishin. It was, essentially, a Curse Seal jutsu by technicality, more so by the fact that said planted seal was a more like a brand. Only the caster could remove it.

Kimimaro had no Hiraishin, but many things and people could certainly stand to have a few explosive or...interesting seals on them.

Like this simple one that would, theoretically since he'd only just made it, infuse the surrounding cells with uncontrolled Yang chakra and cause instantaneous growth of tumours. Benign, of course. Hopefully. But fear was a viable weapon and body horror a good catalyst for it.

Body manipulation seemed to be the subconscious theme. Already, he was scribing out equations for how best to induce dramatic heterotopic ossification, simply because he had a very good idea about how skeletogenesis worked, from first-hand experience.

He wanted to hurt something, someone, so bad right now. Wanted them to suffer for hurting Kakashi, scaring Kakashi, and scaring him because thisneverhappenedincanon, he'd screwedupsobad-

Digital Shrapnel whistled through the air instinctively as his senses registered the presence behind him. Thunks of a tree having new holes bored in it. A hiss of pain as the enem-Itachi put a hand to the nick in his shoulder.

Kimimaro was at his side in an instant, shoving a little healing chakra into the shallow wound until it scabbed over. He removed his hand, the hand that had inflicted the injury in the first place.

Hhhhrrhrrhggrlalhlgkekelttyrrr...

A wordless, thoughtless, growl of frustration ripped through his throat and he punched the tree with all the force he could muster. It shattered. Golden-brown splinters exploded under his knuckles, the splitting bark giving a mighty groan as the whole thing broke in twain with a mighty CRACK and a long groan.

It crashed to the ground, birds and small creatures scattering in all directions until the area was silent save for the wind in the leaves and harsh, steady breathing. And a long, low whistle.

"...that bad," Itachi confirmed to himself, his admiration rapidly fading due to the whirling mass of emotions pouring off of Kimimaro. Sometimes this whole Resonation thing was both a blessing and a curse; he was a fucking empath for one single person, who happened to be a manic little gremlin from the future with way too many Issues.

"Why am I still here?" He grouched to himself as he took Kimimaro's unresisting hand and started picking the slivers out. A lazy whine of pain accompanied his ministrations. "Oh shut up, you're fine. I'm fine, it was just a scrape, and it was my fault for sneaking up on you. Shut up. Stupid Shisui, stupid genjutsu, stupid plan, everyone is so stupid, so fucking stupid, stupid fucking splinters, stupid time-travel, stupid stupid Butterfly Effect...'"

Eventually, he ran out of splinters to assign a Stupid to. He paused, looking Kimimaro in the eyes. "You're really fucking stupid. Also scary. Mildly scary." He held up his finger and thumb, a tiny space between them. "This much scary. Because you're stupid. Too stupid to actually talk to someone. I mean, me being here, Resonated and all that, doing some good. Seriously though, use your words. Words are good; except when they're stupid."

"Can I scream hysterically into your shirt please?"

"Sure."

"Hrrrrraaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa-"

Itachi sighed.

"-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaagggggghhhhhh!"

"Are you done ye-"

"HHHHHHRRRRRRAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-"

"Are you do-"

"-AAAAAAAAAAAAAAA-"

"Are you-"

"-AAAAA-

"Are-"

"-AAAAAAAAAAAAGGGHHH!...Okay, I'm done."

"Thank goodness, I was worried that you might pop a lung. Feel better?"

Kimimaro leaned back and took a deep breath, rubbing at his eyes. "Yeah, yeah I'm better. Whoo! Much better. Still worried sick though. Thanks for not holding the whole attacking-you-just-now thing against me-OW!"

"There you go, now I don't hold it against you," Itachi said blithely as Kimimaro clutched his shoulder. "This is, kind of the first time I've seen you serious; and get lost in it. What are you even doing out here, anyway? And...where is here? I've never been to this part of Konoha before."

"Oh," Kimimaro gestured to the sloped rooves peeking through the trees behind him. "It's this old house Kakashi-shishou first took me to when I became his Apprentice. He didn't say as much, but I'm pretty sure it's actually his. As far as I'm aware, he just uses it as an armoury." His face lit up suddenly, as a thought occurred to him. "Hey; come with me a second?"

Gathering up the scrolls and sealing supplies lying in the grass, he led Itachi through the trees and through an overgrown circular stone archway. It was pitted by the weather and strangled by ivy, a long-neglected sentinel to what Itachi could now really see had once been a garden. The overgrown wilderness they had just come from had been a garden, once upon a time. A garden belonging to the modestly-sized, traditional house that Kimimaro was waving to him from the decking of. Who's house had this been? Before Kakashi, obviously.
Flicking his Sharingan on for a few seconds, he could see that the whole place was permeated with seals both old and relatively recent, simple and complex, stand-alone and intricately interwoven.

This was a Clan House.

Obviously, the Hatake Clan. The most simple answer was often the correct one. For a shinobi Clan descended from Rai no Kuni farmers, it fitter the whole 'austere and modest' air they had had.

"Take a look at this, Itachi!"

Following Kimimaro inside, he found his brother gesturing to the inner side of the doorframe.

It was scuffed, and dusty, the paint peeled off long ago, but it was a crest carved into the wood. "That's...not the Hatake crest," he mused out loud. "I don't actually recognise it at all."

"Why, what's the Hatake one look like?"

"Stylized grass and thundercloud," he replied promptly. "Not a mountain ridge and a small circle with radiating lines. I guess it could be from an extinct family, maybe a merchant?"

Kimimaro shrugged. "Maybe some vassal family to the Hatake moved here? And when they died out the holdings passed to the Clan? Any visitors from the Hatake Retainer Family could use it a place to stay, I suppose." He tucked his hands in his pockets and ambled over to the hallway, raising his voice to carry as he went. "It's got some nice big rooms, some pretty up-to-date plumbing, and Kakashi-sensei doesn't use it all that...much."

Alerting by the sudden apprehension in his brother's voice, Itachi hurried over. He found Kimimaro in a large, empty room, probably used for dining or as an office, once upon a time. Traditional paper walls, the tatami mats gone with only floorboards remaining...and a large dark stain in the wood, which Kimimaro was looking down at.

"I think I can guess why Kakashi-shishou doesn't live here...anymore."

"What?" Juugo shrugged self-consciously. "Sure, I don't know him all that well personally, I just wanted to...well...'" he petered off, the small bunch of daffodils looking small and fragile in his large hands.

Tenzo, as ANBU Bear, nodded. "No, I get it. Thanks for stopping by; it's nice to see a friendly face. How's things as a trainee veterinarian?"

"So. Much. Reading," Juugo grouched. "Look, I've gotta get back; I just came to drop these flowers off, really."

"Sorry, security measures. I can put them in his room for you though?"

The flowers were handed over, "sure," and it only took Tenzo a minute.

"Good luck with the studying, Juugo-kun," he waved the boy down the corridor until he disappeared from sight. Tenzo paused there, in the empty corridor, conflicted between staying, or leaving for the assignment he was already very late to.

He ducked into Kakashi's room once more, forcing himself to drink the sight of his longest and best friend in.

The thin hospital shift was not flattering, the soft pulsing glow of the Iron Lung visible through the grey-green material. The corner of the paper seal that kept his heart beating peeked out from under the low neckline. A urinary catheter snaked out from under the blankets into a bag attached to the bedframe. The unruly mop of silver hair, forehead-plate long removed, fell down over closed eyes and left them in shadow. Tenzo combed it back with his fingers as best as he could.
An oxygen mask was carefully hooked to one side, only to be used if blood oxygen was low since the Iron Lung kept him breathing. The usually ever-present face-mask was gone. At first, the oxygen mask had substituted adequately, but now...

Pale skin, a strong jawline. Chapped lips, a slightly narrow nose. A small mole to one side of the chin. Mouth a little open, a glint of the tip of a canine at each slow inhale.

Suddenly self-conscious of the close scrutiny he was putting Kakashi through, Tenzo pulled the thin bedsheet up so it covered Kakashi's lower face, checking that it wouldn't obstruct his breathing.

Give Tenzo a target, he'd kill them.

Torture him, he'd break out.

Show him a supply route, he'd destroy it.

A wound? Heal it.

A base? Infiltrate it.

But confront him with this kind of helplessness and he was frozen. He was useless, and he did not like it one bit.
He'd thought his days of weakness were over, when he gained his Curse Seal and officially left the life of a Career ANBU.

But now?

"You better wake up," he whispered out loud. "Or I will burn those stupid bodice-ripper novels, so help me." The thought of Kakashi's face at such a thing almost made him chuckle. Almost.

With a small trickle of chakra, a twig sprouted from his hand, leaves unfurling. It was no flower, but it was something. It joined the bunch of daffodils in their glass, and Tenzo was gone.

The sun was bright, and warm, and beat down heavily on his black cloak. But he was used to it, and the journey was quick.
Ah, as expected; Naruto had not gotten himself to school and was, in fact, still in pyjamas. Tenzo would give him a pass, just this once. But still...

"Naruto Uzumaki!" He bellowed for effect, cloak swirling dramatically with stark shadows playing over his mask as he materialized. "Shouldn't you be at the Academy?"

With a terrified shriek, Naruto leapt clean out of his chair and hid beneath the table. Tenzo merely folded his arms, staying standing where he was.
"I'm disappointed, Naruto-kun; how do you expect to become a great shinobi if you deliberately miss out on your education?"

A defiant sniffle.

"Well?"

"You weren't there," Naruto said flatly. "You'd jus' gone, no note or nuffin'," his voice began to tremble and blur, hiccupping dangerously as he wiped his snotty nose on his sleeve.
Tenzo knelt down, sensing the flurry of confusion and hurt radiating off of the boy.

"I'm not leaving you, Naruto-kun," he said as gently as possible. "I'm sorry about this morning; I would have left a note, but something...bad happened and I had to move fast. And then I couldn't leave until things were stable. I was...upset. I needed to collect my thoughts. I'm sorry for disappearing on you."

Like a switch had been flipped, Naruto's expression brightened up, quickly shifting into a sly side-eye. "Sooo...you' not mad about the Academy~?"

Tenzo grabbed him gently by the collar and hauled the child, squirming gleefully, out from under the table and on his feet. "Oh, yes, I meant what I said, that you shouldn't skip your education if possible. I was prepared to let you off however, if it weren't for the fact that it's the afternoon, you're still in pyjamas, and having a lunch consisting of only fruit and an exorbitantly unhealthy amount of sugar and chocolate?"

"Fruit's healthy, Bear-nii," Naruto scowled smugly, folding his arms. "Lady at the Studen' Dorms said so!"

"No, it's a balanced diet that's healthy; I was standing at the back of the room when she explained the food pyramid," Tenzo countered. "Yes, it's good that you are eating fruit, but how much of the other things in comparison is where people go wrong. Now, put the rest of that sugary monstrosity in the fridge, you can have little bits for dessert over the rest of the week. Then go and get dressed while I cook an actual lunch; afterwards we will do some kunai training."

Face originally sheepish at having his argument undermined, Naruto quickly lit up at the mention of training, scampering off to get some proper clothes on.

Tenzo had barely started to pan-fry some roughly chopped vegetables and spices when his charge barrelled back into the kitchen, dressed, holding a closed fist triumphantly aloft and a smear of blood on his lip.
"Bear-nii, Nii-san! It came out, look look look!"

He opened his hand and in his palm lay a small tooth.

"You poked it too much, that's why it came out bleeding, you brat," Tenzo said exasperatedly, ruffling the mop of golden hair anyhow. "But yeah, congratulations. Remember to throw it onto the roof, or the new one won't grow in straight."

He pouted. "But I can't throw that far! It'll just go into Kimi-san's window 'cause he's above me!"

"I could throw it for you, if you like?"

Naruto clutched the tooth to his chest, shaking his head. "Nu-uh."

"Well, it's bad luck to keep it on you, otherwise the Hone-onna will smell it and steal all of your teeth while you sleep."

"Nah, I'm the future Hokage, believe it! I'll just get 'er with a kunai like hyah! and hah!" He enacted his motivation with little mock-stabbing motions as well. Tenzo noted that his stance was nearly on point, and also this was adorable.

"Mm-hm. I wouldn't advise it, Naruto-kun. If you make her angry, the Hone-onna will just steal your bones." Y'know, sometimes folktales were just weird, Tenzo thought privately.

Naruto's face had blanched, expression gormless and horrified like he'd just been smacked in the face with a fish. "Bear-nii?" He asked tremulously. "Is...is Kimi-san a boy Hone-onna?"

"...Actually, considering some of the odd Clan origins out there, I wouldn't be surprised."

"...Nerveweed."

Danzo enunciated the word slowly, in disbelief.
"It is certain? Kakashi Hatake was irrefutably poisoned, with Nerveweed?"

"Yes, Danzo-sama," the masked figure nodded. "He was lucky to survive at all, and his expected recovery is long."

Danzo calmed himself, rising from his seat. He would have time to dwell on the ramifications of this later. For now; a visit to the infirmary. "Walk with me."

The mask bearing a snarl and four round eyes nodded once, before it's owner fell into perfect step half a pace behind the Councilman's shoulder.

Steps silent with long years of practice, the only sounds Danzo permitted himself were the rustle of robes and clack of a walking cane he preferred to let others think he needed. The lie was not without it's grain of truth. He had indeed been hamstrung many years before, in an ambush with a particularly slippery Kumo-nin, but he had healed better than expected.
The same could not be said for his arm, which had been crippled beyond use by a(now very deceased, as a sword shoved through the throat would attest) nin from Iwa with an unusual Kekkei Genkai for explosions. Of course, Danzo had also used this apparent infirmity to his advantage. Everybody knew that that arm was a mere withered frame, so why look any closer? There was nothing to see.

Before his proclivities revealed his traitorous nature, Orochimaru had gifted him an arm in payment for the valuable medical equipment Danzo had purchased with his own coffers. Danzo was still not entirely sure that Orochimaru had not grown the pale-skinned man in a vat somehow, given the remarkable malleability of the white flesh. It had accepted the implants of numerous Sharingan, discreetly harvested from the battlefield dead by ROOT operatives shadowing behind like so many crows, with no trouble at all. It had even taken Hashirama Senju's DNA, though not to the extent Danzo had wished.
All these visceral secrets were kept safe from sensors and Hyuuga by heavy gauntlets and bandages, all inscribed with Fuuinjutsu.

And speaking of Fuuinjutsu...

ROOT had it's own infirmary, as a necessity. Currently, it housed only one patient, and the one Danzo urgently needed to question.

"Heisei, wake him," he ordered, the ROOT medic hesitating before waving a hand over the boy's face. Golden eyes snapped open in a panic, limbs struggling against the straps that held them in place.

"Peace, Fuu" Danzo ordered, flaring his chakra to pull the boy back to reality. The child duly stilled, breathing calming as he awaited orders. "The mission is over. Though, there are some discrepancies I need cleared up." He eyed the tattered straw doll inscribed with a curse seal that lay on the bedside counter. "Do you recall the one who attacked Yashiro Uchiha, as you sat inside his body?

The mouth worked silently for a moment, before a hacking cough wracked his chest and a hoarse whisper emerged. "...Man...with a mask...orange mask...spiral mask...black hair...long, spikes...'" He paused, sucking down lungfuls of air with a thin whistling sound. "...black pole...went right through...touched...like claws, claws in my chakra and I couldn't, I couldn't feel, abort mission, had to, abort abo-or-rt..."
Eyes glazed over and he began to thrash about once more.

The medic, mask adorned with scales and two vertical stripes over the eyes, sent him back into unconsciousness.

"Wake him," Danzo ordered a second time.

"Danzo-sama," Heisei objected uncertainly. "He sustained serious damage to the chakra pathways in his brain. I can fix it, with time, but he should remain-"

"Heisei." The cane thudded against the floor, punctuating the reprimand. "This Village is in great danger. Yes, I would like him operating at full capacity, but he has answers I need. It is imperative that you wake him. Whatever damage this causes will not be a sacrifice in vain."

"Hai, Danzo-sama."

Fuu's eyes opened once more.

Danzo leaned over the young ROOT operative's slight form. "Tell me something, Fuu. I ordered you to possess Yashiro Uchiha and use his Sharingan to have Kakashi Hatake poisoned. I needed Hatake out of commission but briefly, Yashiro Uchiha was the real prey. So tell me, why is Kakashi Hatake at death's door from a lethal dose of Nerveweed, when I gave you a packet of powdered Goldenchain seeds?"

Goldenchain is a legitimate name for the Laburnum tree. It's quite poisonous, exhibits very similar symptoms to Hemlock, but is rarely fatal.

For those of you who were wondering why Pain killed Yashiro...no. Pain is busy at the moment.
But according to the Wiki, the Black Rods are literally just manifestations of willpower and a jutsu that can be taught/learned. Though it apparently helps if you're part Senju/Uchiha, I dunno. But yeah, Obito has the Black Rods.

And Tenzo unwittingly contributes to Naruto's fear of the supernatural.