AN: Welcome to my Itasasu soulmate AU :) It takes place in the canon universe, but with the addition of soulmates. Before starting the story, I want to make it perfectly clear - YES, this is a Itachi/Sasuke fic. If that isn't your thing, it's understandable. But any hate comments for the pairing left on this story will be deleted. If you don't like, then don't read. It's that simple.
As you have noticed from the rating, this story will eventually have mature content. But if you came simply for that, you'll probably be disappointed - the focus of this story isn't on the sexual/physical relationship Itachi and Sasuke have. It's on the emotional one, something I often find is lacking in most Itasasu fics I've read.
Also, this story does begin when the two brothers are very young. There will be no sexualizing of children in this story, so nothing like that happens between them until they are both older. Their relationship starts as completely platonic, if slightly deeper than normal siblings, and grows beyond that slowly as they become older.
This story starts out mainly canon compliant. But it will eventually deviate and take its own path :)
Chapter One
Itachi
Soulmates. Itachi remembers the day his mother first explained the concept to him.
He's four years old, sitting on a chair at the kitchen table. His legs don't quite reach the floor, and he's swinging them back and forth. He stops when he realizes he's doing it, because it's childish and his father would scold him if he saw it.
His mother is at the sink washing dishes. She's singing a song as she works, and Itachi is content to just watch her. He likes her voice. It's very soothing.
Her sleeves are pushed up to her elbows to prevent them from getting wet. And that's when Itachi sees it: the inky black letters against her left wrist.
"Kaa-san," he asks, "what's that on your wrist?"
Looking back, he's sure that this couldn't have been the first time he's seen it. But it's the first time he can clearly remember it, and the first time it truly catches his attention.
Itachi doesn't consider that it might be something he shouldn't ask about. He's a quiet, well-mannered child, but he's also very curious. He wants to know things—to understand them. He wants to understand everything.
Mikoto's movements stop, her body tensing in surprise at the question. For a moment, Itachi worries he's said something wrong. He didn't mean to upset her.
There's a slight pause—but then the line of her shoulders relaxes. She turns off the faucet, and when she turns to face him, her smile immediately puts him at ease.
"No one's told you about soulmates yet, have they?"
Soulmates.
It's an extremely familiar word—but not one he fully grasps the meaning of. It's the type of word that he hears regularly passed around in conversations, that has cropped up in dozens of his books. He's been able to puzzle it out a bit through context, but he still doesn't understand.
He knows soulmates are something adults have. They're someone that you love and spend your life with.
He doesn't understand what they have to do with the words on his mother's wrist.
"Soulmates," Itachi says. The word feels strange on his tongue. "You mean like you and Tou-san?"
Mikoto's mouth tightens. There's a flicker of something in her eyes, but Itachi doesn't have a word in his vocabulary to accurately describe what it is.
She pulls out the chair next to him and sits down, that tightness softening.
"Your soulmate is someone very special to you," she explains, "and there's only one of them in the whole world. They're the other half of your soul—the person who completes you. You cherish them above all others."
Itachi can't quite grasp the words. He loves both of his parents, but the type of love his mother is describing seems too big for him.
"What does that have to do with your wrist?"
"Well—" Mikoto grabs his wrist, turning it up and brushing her thumb over the pulse-point. "This is where your soulmate's name will appear one day—when you're around twelve or thirteen. We're already connected to our soulmates, of course. But the names are the universe's way of giving us a bit of direction."
Itachi stares down at his blank wrist, trying to imagine a name there someday. The name of his soulmate.
It's difficult to imagine. He has dozens of questions, always ever-curious as to how the world works—but he doesn't ask any of them, clearly recalling the name scrawled across his mother's wrist.
It wasn't his father's.
"Tou-san isn't your soulmate," Itachi says.
The fingers around his wrist tighten. His mother exhales between parted lips, her eyes briefly slipping closed.
"…No," she says quietly, after a long pause. Her fingers fall from his wrist. "He isn't."
She bares her own wrist to him, the way someone might bare a secret.
Kushina Uzumaki, it reads.
"My best friend," she explains without prompting. "Or, she was. We're not as close anymore, but… we still talk occasionally."
The name is familiar. Itachi stares down at it, pulling on the thread of a memory that refuses to properly focus.
"The woman with the red hair," he recalls, remembering his mother stopping in the street to exchange words on multiple occasions.
Mikoto smiles, something wistful in her eyes. "Yes, that's her."
The softness in her voice, her expression, her eyes—it confuses him. He shakes his head, pulling his gaze from her wrist. "But—Tou-san—"
"I love your father," she says to him—sincerely, without hesitation. "Don't ever doubt that."
Itachi can tell she isn't lying. But he doesn't understand. If your soulmate is supposed to be the one who completes you, the one you spend the rest of your life with—then how can his mother's soulmate be somebody else?
Itachi doesn't understand love, not really. But he can recognize it in his mother's eyes, in the careful way her lips form the name scrawled onto her skin. Maybe she does love his father, but she's never spoken his name like that before.
"But you love her," he says.
"I do," she admits, a shadow of old pain in her eyes. "I always will. But we aren't meant to be. Your father has made me happy, and I don't regret one second of our life together."
"But she's your soulmate."
Mikoto smiles sadly. "I'm not hers."
Itachi blinks. That can happen? he wonders, and thinks that it doesn't make sense. If soulmates are two people meant for each other, then how can one half be meant for somebody else?
Mikoto brushes his hair out of his eyes. "Don't be sad for me, darling. I told you, I'm happy with what I have."
Itachi bites his lip. He stares down at his blank wrist, feeling the beat of his pulse beneath his skin.
"I don't think I have a soulmate," Itachi says.
His mother is thrown by the words, sitting back slightly. "What? Why would you think that?"
Itachi shrugs. He doesn't know how to explain the feeling in words—that he can't imagine loving anyone that way, or anybody loving him.
"Just a feeling," he says, and he doesn't understand why his mother looks so sad.
Itachi goes to the library to research everything he can about soulmates. Even if he doesn't think he'll ever have one, he's still interested. It's a subject unknown to him, and Itachi doesn't like things being unknown.
He likes to understand everything.
He asks the librarian to direct him to the correct section. She looks at him strangely when he begins piling the large books into his arms, and she asks him if he wants something simpler, more suited to his age—he tells her thank you, but that he's fine with these ones.
At four years old, Itachi already knows he's a genius. The eyes gawking at him as if he's some strange creature aren't anything new.
Itachi stays in the library all afternoon, buried deeply in books. They have a lot to say on the subject of soulmates, and there's so much that Itachi doesn't know. He devours every scrap of information he can find.
He learns that there's a connection between every pair of soulmates. Like his mother said, it isn't the name on their wrists that ties them together—that's just a helpful guide. The tether between the two souls exists long before that, drawing them together.
With particularly strong bonds, sometimes they can share each other's emotions. Sometimes they can use it to determine the other's location.
Itachi learns all about soulmarks—and how they aren't always the same. There are unreciprocated bonds—or one-sided bonds, as they're more commonly called. The type of bond his mother has, marked by the name of a person who is marked by someone else. These types of bonds are rare, but they happen.
Also rare, there are people who don't have soulmates at all. Their wrists stay blank, a name never developing.
Soulmates can be different things to different people. Usually, the bond is romantic; your soulmate is the person you marry and start a family with. But not always. It can be platonic, too. Best friends who have grown up side-by-side—no physical attraction is necessarily required in some cases.
The soulmarks develop during puberty. From what scientists have begun to ascertain, it has something to do with chemical changes in the body. At first, the name on your wrist will appear as nothing more than a slight smudge—and in the time-frame of a few days, the letters will become clearer and clearer, until they're finally fully developed.
One name, written on a person's left wrist in clear black letters. Why the left wrist? No one knows.
Itachi reads everything he can find on the subject of soulmates. When he finally goes home, he still has so many questions.
What are soulmates, really? Why do some people not have them? Why are some bonds unreciprocated? Does a person always end up loving the name on their wrist?
All of these unanswerable questions swirl in his head, as he rubs his thumb against his own blank wrist.
In the books at the library, Itachi also learns about broken bonds—soulmarks that have turned gray and dead, forever scarring a person's skin. He reads personal accounts written by people whose soulmate has died, how it felt as though their souls were ripped in two, how they never felt whole or happy again. An unbearable, gaping emptiness forever inside of them.
Itachi shudders as he remembers the words, and thinks that being markless wouldn't be so bad. He can't imagine being anyone's soulmate, anyway.
Itachi knows that there's a war going on. But until he saw the fighting for himself, he wasn't aware of what that word really meant.
Bodies are strewn everywhere. It's horrible and ugly, and he wants to shut his eyes against it.
His father won't let him. His father forces him to look.
The smell of blood is thick in the air, even as the rain begins to pelt down and wash it away. Itachi stares out at the battlefield littered with dead shinobi, their faces frozen and twisted grotesquely, their eyes dull. He feels sick to his stomach.
Fugaku drops a heavy hand onto Itachi's shoulder. His wrist is bare, markless.
"Burn this sight into your eyes, Itachi. Never forget it."
Itachi pulls his gaze away from his father's wrist. His eyes sting, but he refuses to cry.
He looks out, over all of the corpses. He thinks about life. He thinks about death. He thinks about what it all means, and how insignificant it all is.
If he does have a soulmate, he feels sorry for whoever it is.
The war is over, and the Uchiha Clan burns all of their dead. His father's sister is among them, but Fugaku doesn't cry. Her soulmate does, though; harsh, gut-wrenching sobs that make people turn their eyes away.
Itachi doesn't understand it. Life, death—it seems all the same to him, and he can't find a meaning in any of it.
Later that day, Itachi throws himself head-first off a cliff. He isn't sure why he does it. He isn't trying to kill himself—he doesn't think he's trying to kill himself.
It doesn't matter. The crows save him.
Itachi is five years and almost two months old when his little brother is born. For his entire life he's lived in a world made up completely of gray, and suddenly, it's like everything bursts into color.
"Itachi," his mother says. "Come meet your baby brother."
The baby is swaddled up in a bundle of blankets, held against Mikoto's chest. His skin is pink and wrinkly, with a tuft of dark hair. His mother places the baby in his arms, and Itachi freezes, staring down.
Dark eyes peer up at him from a small face, and Itachi is abruptly aware that he is holding the whole world in his hands.
"Did you decide on a name?" Fugaku asks. His hand settles on Itachi's shoulder, but Itachi barely registers it.
"Sasuke," Mikoto says, smiling. "His name is Sasuke."
Sasuke, Itachi thinks, and the name instantly engraves itself onto his heart.
The newborn baby grasps one of Itachi's fingers, pulling it into his mouth. Itachi smiles, laughing slightly, and his heart feels so full it could burst.
For the first time, life feels like it has meaning. He has a reason to pull air into his lungs each morning.
I promise, Itachi vows, holding his brother tightly against his chest, I'll protect you no matter what.
Being a big brother brings a purpose into Itachi's life. He has a reason to exist now, and that reason is Sasuke.
His parents are often so busy. The clan must be managed, and their attention is constantly split. Itachi thinks their priorities aren't quite where they should be, but since he's being groomed to take his father's place someday, he keeps his mouth shut on this opinion.
His parents are gone, and Itachi makes sure his baby brother is taken care of.
He begins attending the Academy that year. He hates it there, and all the children hate him. Except for the girls, who are always staring at him and asking him who he thinks his soulmate is—as if Itachi is supposed to know, he's only five. Don't they know how soulmates work?
Itachi rushes home each day to Sasuke. On the good days, when his father smiles at him instead of snapping, he can even get the man to teach him a jutsu.
Itachi doesn't think much on soulmates anymore. He's always said he probably doesn't have one.
There's an ominous chill in the air. Sasuke can feel it, too; Itachi rocks him back and forth, attempting to soothe his distressed wailing.
"There, there. It's okay, Sasuke—your big brother will protect you."
A deafening roar splits the night, and that's all the warning Itachi gets before parts of the compound go flying. A great big tail hits them, crushing buildings and people and everything.
It's chaos, after that. Everyone is screaming, tripping over each other, people so much taller than Itachi. Debris and bodies and blood are everywhere, and the Nine-Tails is shaking the ground that he's standing on—
Itachi doesn't know what is happening, but he clutches Sasuke to him and uses his body as a shield.
Running is hard, almost impossible. People are fleeing, no regard for their surroundings, bumping into him and knocking him to the ground. Sasuke is screaming in his ear, and Itachi's heart is pounding like a jackhammer in his chest.
Safe, Itachi thinks. Have to get him safe, have to get him safe…
There's a girl from the Academy that Itachi knows—an Uchiha. She's crying as everyone around her runs, sobbing for her mother.
Izumi. Itachi thinks that's her name. She's one of the ones who is nice to him.
Itachi saves her life, gripping her hand and pulling her away just before she's crushed. She clings to him fiercely, her fingers twisted up in his shirt and her body shaking.
"Itachi-kun…"
"You're safe now," he tells her. "Come on. We need to get out of here."
When he finally reaches the shelter, he leaves Izumi with her mother and curls up in an empty corner. He shakes and shakes and shakes, clinging to his brother like a lifeline and refusing to let anyone close.
He's never felt such fear in his life.
"You're safe," he whispers, rocking Sasuke against his chest. "You're safe, you're safe, you're safe…"
Konoha is saved. But the price was too high, and no one is celebrating.
Three days later, the entire village comes together for the funeral. Konoha's entire population mourning the death of their Fourth Hokage—the brave, honorable man who sacrificed himself to save them.
For the next month, Itachi listens to his mother cry herself to sleep. The skin at her wrist has turned a horrible gray.
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