Casimir Effect
Hashirama sits by a chest of his mother’s belongings, fingers tracing the shape of her golden kanzashi, and wonders about what kind of woman she had been. Kind, his grandfather had said. Intelligent and creative, steadfast in her beliefs, and yet, gentle in her manner. She wrote poetry and painted in her free time. She made perfect cups of tea. She could play the biwa; she had done so in her first meeting with her father-in-law and recited the Tale of the Heike instead of playing something more palatable as she had been advised to because she thought a warrior might appreciate the epic more. She loved children.
“She prayed at the Sacred Tree on the first of every month after she learned she was pregnant with you,” his grandfather said. “She loved you before she even knew you.”
She loved him enough that she died to give life to him. The entire clan praises her for it, telling Hashirama he gets his bravery and capacity for love from her. That the ancestors and spirt of the Tree were so moved by her sacrifice, by her gift to him, that they too bestowed their blessings upon her child to make it up to her for a short-lived life. That his mokuton is a culmination of her love, her hopes and dreams for him. A reward for her sacrifice.
Her name had been Kata. Worthy. How fitting for a woman who would bear the first wielder of mokuton in over a century.
Hashirama wonders if she would have liked him. If she’d approve of his dreams, of his accomplishments and failures. If she would be proud.
He hopes so, anyways. Hashirama doesn’t know her either, but her loves her too. She sounds like someone he would get along with.
If Kata had been alive, it would have been her duty and privilege to gift the kanzashi heirloom to Mito as per the Uzumaki custom wherein the mother-in-law does so to welcome the new bride into the family. Had Maiya survived, perhaps Hashirama’s stepmother could have performed the duty in Kata’s stead. Unfortunately, since neither of his mothers lived long enough to see him marry the Uzumaki princess, Hashirama will gift it to her himself.
Theoretically, he could get some other woman to whom he is vaguely related to stand in for the role, but Hashirama knows it might be seen as a bestowing of some sort of opportunity. It would become a power play on several levels, likening some other woman to his mother and, not only giving her power over the other Elders, but also Mito. It’s a hardly a crime if Hashirama doesn’t want to deal with such petty politics on his own engagement day.
At least the kanzashi is pretty enough to compensate. An arch shaped comb, expertly crafted from gold and carved with hundreds of tiny flowers so delicate that they can only be seen from up close, the centre of each one inlaid with a tiny crystal that gleams when it catches the light just so.
It also comes with a slot hidden along its base that hides a long senbon so thin, it may as well be a single strand of gold.
In a few months’ time, Mito will turn nineteen, and it will be time for them to commence with an official courtship period that will conclude with an engagement. Hashirama will have to make the trip to Uzushio himself this time.
It will be his first meeting with the woman who is to be his future partner, the one he will share his joys, burdens, home and life with. She will preside over his clan with him. She will be his equal, his proxy, his complement in every way that matters.
No pressure. Hashirama isn’t mildly crippled by the fear that she will find him repulsive and hideous and they will make each other miserable for the rest of their lives. Everything is fine.
He knows, on some level, that it isn’t true. Tobirama likes Mito, and he doesn’t really like anyone as a general rule of thumb, so that’s as big a glowing seal of approval as a person can possibly get. It means that even if they don’t fall in love, they will probably at least come to a friendship.
Both the Senju and Uzumaki are flexible with taking lovers outside of a formal marriage agreement so long as all parties involved are consenting adults. It’s hardly as though this arrangement is going to suck the romance out of Hashirama’s life.
Still, he worries.
Because he wants this to work. He wants to befriend Mito, and he likes the idea of this fated connection between them maybe leading to something more genuine and loving. He wants for there to be love between him and his wife, something to tie them together that is more than a contractual obligation to produce heirs of combined lineage for the clan.
Or perhaps this is another bout of wishful thinking.
His father would call him childish and exasperating for fretting over his duty this way. Tobirama would call him an idiot if he knew, though for different, kinder reasons.
Would his mother tell him she understands? Had she too been afraid? Had she wanted love and romance just like him?
Hashirama sighs and places the comb back into its ornate box, patterned with juniper and orchids. He rises to his feet and leaves the room of his dead mother’s things.
The final Trial, by Kitai’s choice, is a game of shatranj.
It is held in the room that functions as the clan head’s audience chamber where they receive requests, complaints, gifts, and guests. On a marble pedestal at the heart of the chamber sits a board carved from fragrant sandalwood, emerald pieces arranged on one side and ruby on the other.
“Very ceremonial,” Tobirama remarks from his place by his grandmother, one step to the left and two steps back.
Kitai lifts and eyebrow. “The robes didn’t clue you in?”
They’d certainly been a decent hint when Tobirama had found them waiting outside his door. A traditional tunic tailored to his exact measurement in deep red linen along with a black silk chlamys embroidered with laurel leaves in threads of gold, fastened at his shoulder with an obsidian pin bearing the Hatake crest.
“You are anticipating his win,” Tobirama concludes. There would be no reason for all this formality otherwise.
“I trust him to prove his worth,” Kitai corrects evenly. “If he does not…”
Arching a brow, he prompts, “If he does not?”
“Maybe I’ll nominate you for the Trials?”
He rolls his eyes openly. “Come off it. You know as well as I do I can accept no other mantle as my brother’s Champion.”
“As if you ever needed an excuse to spurn us for him,” Kitai huffs, but there is no heat behind her words. The Hatake of all people know how to value loyalty sworn in blood. No one here questions Tobirama’s allegiance anymore; not since he forced them all to respect it.
Before Tobirama can reply, the doors are pushed open to admit Iroha, dressed similarly in robes of green and ebony. When the boy spots the shatranj board, he relaxes visibly, though his relief doesn’t last long once he realises who he will be playing against.
“You’re my opponent?” he asks incredulously, sliding into place opposite from Kitai.
Kitai’s lips twitch. “It is traditional for the Trial of Sovereignty to be some sort of duel between the previous clan head and their heir.” She nods to the board. “It is my right to have the first move. If you are ready, we shall begin immediately.”
They play for a long time, well into the evening with the sun beginning to dip behind the horizon, both of them taking long moments to contemplate each move. The game that unfolds is an enjoyable one from Tobirama’s perspective as a spectator. They are both good strategists, thoughtful and decisive. Similar in ways all masters and students are.
But Kitai is better, and Iroha knows it too as they enter the final stretch of the game.
“I will lose in two more moves,” he observes, a defeated sort of smile on his face. He looks tired but satisfied with a match well played.
Kitai smiles back at him, eyes warm. “You did well, child,” she says. “Do you know why I chose shatranj?”
He does not give the obvious answer that they could only have duelled in so many ways when Kitai can no longer fight physically. Instead, Iroha cants his head in thought and says, “You wanted to test what kind of commander I’d be.”
“Yes.” Kitai’s smile widens. “And you have far exceeded my expectations, Iroha. I could not have asked you to play a better game. You will make a worthy heir.”
Tobirama blinks.
“I resign,” Kitai says, folding her hands together in her lap. “Congratulations on your win, Iroha.”
Eyes widening, Iroha says, “Wait, that means—”
Before he can finish, Tobirama cuts him off by bowing at the waist, the back of his neck bared in deference. “I offer my loyalty and respect to the clan heir. Please accept my greeting.”
An expectant pause. Then, “I accept your greeting, Tobirama. You may rise.”
Iroha’s face is a bright red when Tobirama lifts his head, eyes flitting about the audience chamber as though looking for an escape. Tobirama exchanges an amused look with his grandmother. What will their new heir do when the entire clan does the same to pledge themselves to him?
Turning to the door leading into the eastern wing, Kitai calls, “Bring in the wolves. We will proceed with the bonding ceremony.”
The bonding ceremony is a relatively simple affair. The heir to be bonded and the wolf that is to be their lifelong companion both drip a bit of their blood into a bowl of water and redwood sap before each taking a sip. With the magic having witnessed the worthiness of the heir, a symbiotic tie is created between them for life. The heirs sustain the wolves’ ability to live in the human realm, and the wolves devote themselves to their partners until the end of their natural lifespans.
Iroha’s wolf is a young thing called Sumire who has not yet finished growing, much like the clan heir himself. Her coat is a deep mahogany, white tufts peeking through in some spots. She is a much louder, energetic personality than her newly bonded companion who is steadily looking close to fainting. Kitai does nothing to intervene for his sake, looking content to watch Sumire run in circles around and chatter away at Iroha.
“It has been a while, cub.”
Tobirama freezes before turning around and bowing his head in respect to the massive wolf. “Hinode-san. I did not know you would be here today.”
She draws closer, gently bopping his chest with her forehead before lifting her head to carefully bump noses with him in greeting. “I thought I might find you here when I heard your cousin is to be heir. You have not come to see me.”
He doesn’t wince as part of him wants to, carding a hand through sleek white fur in apology instead. “I’m sorry,” he says sincerely. “I’ve been busy.”
Hinode watches him with intelligent obsidian eyes. “I could stay with you, you know,” she says softly.
Tobirama sighs and presses his forehead to hers. “I don’t want to take you away from your pack.”
“You’re my pack too.”
He knows she means it. Hinode had insisted on living with him when the Hatake had moved to Konoha, but at least then she’d had the rest of her family within the village. It is different now when they are still in different countries.
Hinode whuffs at him chidingly. “You are your mother’s son, Tobirama. That makes you mine. Never forget.”
“I know,” he acknowledges quietly. Her bond had been to his mother when Maiya had been made heir, and it is sustained now by Tobirama who has Maiya’s blood running in his veins. “You have a litter of your now though.”
If wolves could roll their eyes, Tobirama is sure that’s what Hinode would do. “Your siblings will live with us as well obviously.”
His mouth twitches. “Obviously,” he repeats agreeably. “And Masa-san?”
At this, she grows silent. “He still has lessons to learn alone.”
“So, you haven’t seen him either,” he deduces.
“I know where he is,” Hinode admits. “I can feel it in his blood just as I can in yours. But I cannot give him forgiveness when he is too afraid to ask for it.”
Tobirama sighs. “I don’t know what I’d say to him even if I did see him.” Not even an entire lifetime’s worth memories could prepare him for that confrontation.
“It’s not like you did anything wrong,” the wolf states. “Masa was at fault for what he said. You did well by defending your brother.”
Inclining his head, Tobirama says, “I know. I will not apologise. But…” He shrugs, unsure of what to say except for, “He is my mother’s brother.”
Hinode shakes her head. “A reckless fool is what he is. Enough about him. I wish to hear more about what you have been up to. Tell me about your little inventions.”
And, well, if there’s one thing Tobirama is always happy to talk about, that would be it. Truly, Hinode knows him too well.
The first sign of trouble is the children falling ill.
It doesn’t seem too worrisome at first. Fevers, runny noses, coughs. Then the spots show up, the coughs get worse, the fevers don’t reduce. The illness spreads among the children of the little community who all play together, and then it catches with the elderly and the parents.
It happens so quickly, Izuna doesn’t even really register it until they’re in full blown crisis prevention mode trying to keep the disease contained so it doesn’t wipe out the entire settlement with how quickly it seems to catch. There are only two medics in the whole village, a middle-aged couple who are quickly at their wits’ end with trying out remedies that help the symptoms sometimes but are certainly not a cure.
Tomoya, the daughter of the Daimyo who has been left in charge, swiftly orders isolation of the sick to keep the illness contained before sending for more skilled specialist healers. They prescribe stronger fever reducers, remedies that clear the airways and prevent some of the observed complications like diarrhoea and ear infections.
Some people get better eventually. Others…don’t.
They set up a medical camp for the affected to keep them separate from other patients although most people have begun avoiding the clinic anyway. Within a few weeks, the place turns into a veritable ghost town as its inhabitants take to hiding behind closed doors where they hope the illness will not reach them. Whatever sense of comradery or community might have been developing here all but evaporates within a fortnight.
Uchiha Kazane and Kazuki, twins who’d been helping guard the camp under Izuna’s orders, start showing symptoms. Izuna hates that he doesn’t know how to help them.
“Should we send for one of our healers?” Gen asks lowly, mouth pressed into a thin line. Three of her own are infected after all. One of them has developed pneumonia in their immunosuppressed state as well. “Perhaps iryo-ninjutsu will be helpful.”
Eizan frowns. “Will they get here in time?” he brings up hesitantly.
Neither of them answers that. It is unlikely; the journey is long and takes perilous roads. Fire does not see a lot of heavy rainfall during spring, but Iron is known for landslides in this weather given their rocky hills. It would be risky, especially when healers are a precious commodity for a shinobi clan.
“Does the Hatake clan not have healers?” Izuna asks.
The general folds his arms. “We do, but they are not specialised in illnesses. Something about our agreement with the spirits helps us hold out against most infections though the specific details are known only to the clan head and heir.”
Izuna is instantly jealous. The stupid bakeneko that hang around the Uchiha compound aren’t half as useful; they just scare children and try to lick the lamp oil.
“Will you write to them anyways? If the sickness targets chakra, then the civilian healers would never know. It would be better than nothing,” Gen says, leaning forwards slightly, hands braced against the table.
“How long would the journey take them?” Izuna questions.
“Four days. Maybe less if they’re able to push it,” Eizan replies thoughtfully. “I will send word.”
Seeming relieved, the usually reticent Shimura’s shoulders slump. “Thank you.”
Izuna echoes the sentiment sincerely. He tries, almost compulsively, to bring back all the shinobi under him back home alive, which is part of the reason he is usually assigned to solo missions to preserve his mental health. The illness has not proven deadly to everyone, but it has been bad enough that he feels genuine fear for the twins.
When he learned of the outbreak, Madara asked if Izuna thinks it would be best for the Uchiha to withdraw from the mission despite their contract period extending to another month. Logically, he knows the answer is yes, but he also knows that the twins simply would not make the trip back alive and he can’t bring himself to leave them behind. They’re Uchiha; they stick together through everything. It’s why none of the others have left even though Izuna gave them the option because he understands the risk that they’re all taking by staying around a disease that seems to be airborne.
He’s praying that the disease turns out to be some sort of chakra targeting virus, something that the Hatake healers can hopefully cure, because he doesn’t want Kazane and Kazuki to die like this, shivering and in pain, stuck miles and miles away from their home and family.
Izuna doesn’t think he can handle carrying any more corpses back home.
“It sounds like measles,” Tobirama comments after reading the letter his grandmother slides to him over breakfast.
It had arrived late last night apparently, carrying an urgent request for medical assistance with a disease outbreak at a refugee settlement the Hatake are helping the Daimyo establish to rehouse the people displaced by the samurai wars.
“You are familiar with it?” Kitai asks, brows rising.
He hums, sipping at the strongly brewed herbal tea his grandmother favours. “I’ve heard it comes from Wind. They requested aid from Fire to help develop a cure.”
“Is there a cure?”
Tobirama thinks about the timeline and nods slowly. “Yes,” he decides, “although it is not so well known yet. I didn’t realise the disease had found its way here.”
In his future, Fire only had a measles epidemic almost fifteen years from now, with a variant strain of the virus that latches onto chakra coils. Konoha’s healers had to help the scientists in the Capital with the development of a modified vaccine for that. It had done wonders for their medical tourism and relationship with their Daimyo.
“Eizan says some of the shinobi have been infected, though none of ours. So far, there is a death toll of forty-seven, and ninety-six patients are still infected,” Kitai reports.
“That must be devastating for a community of what—some five hundred people?”
Grim faced, she nods. “A quarter of the population. Most of them are children.” Shaking her head, she peers up at Tobirama. “You know my healers aren’t too experienced with sickness beyond common infection. Our blessing keeps us protected from most anything else.”
A blessing that was apparently not renewed following Kitai’s death in the first timeline. Tobirama’s eyes narrow. Could this measles epidemic be—?
“Do you think you will be able to help if I send you?”
He blinks. “You want me to go?”
“If I ask, will you? I know you are not mine to command as I would my people, so I can only request this of you,” Kitai says, gaze resting heavy upon him.
Tobirama softens. “I may bear the Senju name, but I am yours too, obaasan.”
Her smile is wry, but her chakra is warm and encompassing where it wraps around his in an embrace, covering him in her gravel-lightning-blood-birdsong. “It is not so simple. Your brother might protest.”
“He won’t.” Tobirama knows his brother would never refuse the opportunity to help. “You only need to ask, and I will go where you tell me to.”
Kitai exhales slowly, reaching a hand across the table to press to his cheek for a moment, thumb swiping under his eye before she withdraws. “I will let them know to expect you soon then. How quickly can you make the trip to the valley between Mounts Aino and Ryasu?”
He considers the distance, reaching for vague memories of the map of Iron at this time when the samurai settlements and clan territories are still around. “Three days. If I shorten my rest times, maybe two-and-a-half.”
“Good,” she says. “Prepare your things then. May the spirits guide you well.”
Izuna is in the courtyard of their quarters when Gen comes bursting in to tell him the Hatake healer has arrived and is currently being introduced to Tomoya.
“I know it is selfish,” she says as she leads the way to the office, “but I was hoping to ask if he would take a look at my clansmen first. Daiki has been coughing up blood since last night. I fear he won’t have much longer left.”
Izuna keeps the frown well off his face and says nothing. He can understand where she is coming from, and he can admit that he is tempted to do the same, but he has also observed the Hatake here long enough to know the children will get priority, no questions asked. Then perhaps the other at-risk patients such as the elderly and immunocompromised. Shinobi who are known for their considerable comparative health are unlikely to be on the list of priority, especially if there is only one medic who has come.
They round the corner just as Eizan and the medic are leaving the office, Tomoya holding the door open for him in an uncharacteristic sign of respect as she says, “I cannot express to you how relieved I am to hear that. It truly is our honour to have you here. Thank you so much for coming. And thank you, Hatake-san. Know that we will repay this debt to your clan.”
“Not at all, Asahi-sama. There is no debt when so many lives are at stake. We are only doing as anyone should have,” Eizan assures, sounding so painfully sincere that Tomoya’s face softens, and she can only nod in response.
Izuna notices the wolf first. A massive thing, probably coming right up to Izuna’s chest, and with a coat of spotless white fur like winter snow from the Land of Frost itself. It leans into the medic’s side, whose profile is mostly hidden behind Eizan’s large frame, only a head of silvery white hair visible.
And then Eizan turns, spotting Izuna and Gen and immediately smiling as he waves them over, oblivious to the way Izuna freezes and his blood drains from his face. “Come,” the man calls, “let me introduce you to—”
“Senju Tobirama.”
He doesn’t know what kind of expression he is making, the thundering of his heartbeat too loud in his ears for him to focus on anything but the way his breath comes out in too quick, too short bursts of air. At his side, Gen holds herself very still, clearly familiar with the hostile relations that the Iron natives do not appear to be aware of.
For his part, though Eizan is evidently unsure of what is happening, he takes one look at Izuna and immediately places himself back in front of Tobirama, mouth pressing into a firm line. Over his shoulder, Izuna watches as the brief flicker of surprise melts right off Tobirama’s face and becomes a contemplative sort of caution. The wolf is poised right beside him, clearly expecting a fight, while Tomoya watches with an apprehensive tension carved into every muscle of her body.
Tobirama places a hand on Eizan’s shoulder and steps out from behind the man. He is dressed in a more traditional cut of the tunics and shawls that are common in Iron, donning red, black and gold instead of the usual blue, green and brown that the Senju favour. There is a pin on his shoulder bearing the Hatake crest.
Izuna’s head hurts, vision blurring at the edges as the world feels like it is spinning right under his feet. And then, for the first time that Izuna can recall, Tobirama meets his eyes, and everything pulls into startling focus all at once. It doesn’t even occur to him that he could cast a genjutsu on the other man right this very instant, even if it might end with that wolf tearing off his face. His head feels empty with anger or fear or something. Izuna can’t look away, can’t move, can’t breathe.
Senju Tobirama stands across from him, looking for all the world like absolutely nothing is out of place and says, “Hello, Izuna.”