Sasuke is born a few months before the end of the war. Itachi is not there: he's been recruited to set traps along the border. Fugaku is on a mission he couldn't say anything about, the lines beneath his eyes drawn deeper. Mikoto therefore gives birth at home with her sister attending. She doesn't even think of going to the hospital: Uchiha entrust the secrets their bodies hold only to other Uchiha.
It's an easy birth: Mikoto has done this once before, and Mikino has three healthy girls. They both intend for Itachi to marry the eldest.
Mikino wipes the blood off him, cuts the umbilical cord, and places him in Mikoto's arms for her to guide him to her breast. He latches on at once, eyes still shut. Itachi as a newborn had been difficult to nurse: she had learnt to express a little milk to soften the breast enough for him to latch on.
If she focusses, she can feel the tiny developing chakra coils beneath his fair skin. His eyes open a fraction to reveal dark irises. She can already tell that Sasuke - they named him before the birth, in the hope that he'll live up to it - will develop the Sharingan like his brother.
She has produced two strong, healthy sons. One for Fugaku - Itachi was always Fugaku's son - and now one for her. She prefers not to consider what will happen if they lose Itachi: this pregnancy has been taxing enough.
Sasuke snuffles as he feeds, body twitching in the crook of Mikoto's arm. She'd forgotten how small infants were, how animal: it's like holding a rabbit. Outside, the July sky is so painfully blue that she can almost forget that there's a war on.
Mikoto feels his mouth slip from her nipple and adjusts her hold a little as his breathing slows in sleep. She's long envied the ability of infants to simply pass out: she has slept poorly during this war.
She unwraps Sasuke's blanket to swaddle him more securely - and brushes against a tiny raised mark. She turns Sasuke to examine it, making him grumble sleepily.
It's an irregularly-shaped orange-brown mole, curved like a tomoe. Mikoto feels briefly light-headed.
"Oh, my," says Mikino, leaning over to peer at the mark. "That's unusual." Mikoto can see in her face what her mouth isn't saying.
She re-swaddles Sasuke firmly, and draws him close to her belly. He sleeps peacefully on.
"Well," she says, "it looks like Itachi's was only a birthmark after all."
Neither of them believes it.
Itachi-nii has a birthmark on his back, just above his butt. It's a funny lotus-leaf shape, and when Sasuke touches it once at bathtime he can see the shiver run up Itachi's spine. He's never seen Itachi do that, not even when Shisui-nii put an ice cube down his shirt once (he just said 'Aggggh' and pulled it out to chase Shisui with).
"It feels weird," Itachi explains, and asks him not to do it again.
Sasuke likes that birthmark, though he doesn't know quite why. Maybe because it's private: it's only them at bathtime, so only Sasuke gets to see it. It's like his own little part of Itachi, their shared secret.
Sasuke loves his parents a lot, but Itachi-nii is his favourite. And not just because he's his brother: Itachi is objectively the best. All his aunts and uncles and cousins tell him so when they see him. What a gifted boy that Itachi-kun is, they say, and offer him dango. Sasuke doesn't like sweets that much, but he likes hearing other people appreciate how great Itachi is and how he can do things that nobody else can, even adults.
For instance, Itachi always knows where Sasuke is. It doesn't matter how well he hides himself around the compound or how carefully he suppresses his chakra, Itachi always finds him. Mama always finds him too - but she has to activate her sharingan to catch sight of his chakra, whereas Itachi's eyes stay black.
When Sasuke clamours to be told how he does it after his hiding-place under Auntie Mikino's house is discovered, Itachi tells him it's because they're brothers. Among the Uchiha, he explains, many sibling pairs are able to tell exactly where the other is, all the time, even without the sharingan. There's a story that it goes all the way back to Madara and Izuna, who were the closest brothers can be: their bond, he says, is why they were so successful in battle.
"We can be like them, then!" says Sasuke. Itachi pokes his forehead with a smile, but he doesn't say no.
Shisui-nii is taking him for shuriken practice today! Itachi-nii said he was busy, and he was sorry - he looked sorry, too - but Shisui volunteered to come and 'keep an eye on him'.
Shisui-nii is tall with curly hair, and girls think he's handsome: Sasuke heard some of his cousins saying so. He's quiet, like Itachi, but he laughs more. Sasuke thinks that's why they're friends. He'd still rather have Itachi, but Shisui's not bad.
They leave the compound by the back route, the one Sasuke isn't supposed to mention to anybody. It leads into a small forested area, where the kids have set up targets on the trees. Sasuke draws his shuriken, positioning them between his fingers like Itachi-nii showed him, and settles into his stance as he considers the targets. Out of the corner of his eye, he sees Shisui propping up a tree.
Sasuke considers the result mournfully. The first two shuriken are in the centre of their targets, but the last is off to the right by a few centimetres and the third has hit a small branch instead - and no doubt got stuck in it.
He has to scramble halfway up the tree to retrieve that one, but consoles himself with the thought that Itachi would say it was a good way to practice his chakra control.
He goes through the rest of his sets - only twenty, though Itachi-nii does lots more ("The war is over," his father says in his memory, "and we will no longer drill our smallest children like adults.") - practicing throwing two shuriken in one hand. Itachi-nii and Shisui-nii make it look easy, but Sasuke's attempts, while generally landing on the target, rarely end up in the centre. He thinks his hands might be too small.
By the last one he's sweating with concentration and tired; the shuriken slips from his fingers and buries itself in a tree trunk. Sasuke snarls to himself, then makes himself go over to extract it from the wood. He has to use a kunai to scrape at the bark so he can finally wiggle it free. Itachi wouldn't have made that mistake.
His shirt rides up as he drops out of the tree, and he tugs it down absently.
When he turns around to victoriously present Shisui with the shuriken, he finds Shisui looking at him thoughtfully.
"That's enough for today," he says. Sasuke protests, of course, but he's breathing hard and his legs are wobbly, so he doesn't complain too hard. On the way home Shisui asks him about his plans for the Academy, and Sasuke reiterates his desire to start as soon as he's allowed. Shisui listens thoughtfully, hands in his pockets, but doesn't say anything.
"I'm back!" Sasuke calls as he wriggles out of his sandals.
"Welcome home!" Mama says, slightly muffled through the walls.
"Welcome home," says Itachi-nii, appearing in the corridor as if from thin air. He claims it's because he's forgotten any other way, but Sasuke thinks he does it to startle people. Itachi has a funny sense of humour like that.
"Itachi, afternoon," says Shisui briskly. "Do you know, today I have learnt that you and Sasuke really do share everything?"
Itachi-nii's face does a strange thing, but before he can reply Mama appears in the kitchen doorway.
"Good afternoon Aunt Mikoto," says Shisui with a respectful bow. Mama smiles at him: she's always saying that Sasuke should pay attention to Shisui-kun's lovely manners. "Sasuke had to climb a lot of trees during practice today, and I think his scrapes could do with some motherly love. Don't you agree, Itachi?"
"Yes," says Itachi-nii, quietly.
"Some scrapes, you say?" Mama looks more worried than Sasuke's slightly-grazed knee warrants. "Naturally, I'll get that seen to right away. Thank you for bringing it to my attention. Come on, Sasuke." Her tone is mild, polite; but Sasuke can see tension around her mouth.
She takes Sasuke by the hand and leads him to the bathroom and checks him over, even though Sasuke insists he's not hurt anywhere else. Though when she passes her hand over his lower back on the right-hand side it suddenly feels very warm, like a hot water bottle is pressed against it, so maybe he hurt himself there?
He twists around to look at it while Mama applies a sticking plaster to his knee, but there's nothing there.
Sasuke enters the Academy. He's not at the top of his class, but he's near it.
Itachi was the best in his year. Sasuke fulminates all the way home, even when he stops to get senbei.
Itachi won't train with him any more. He just pokes him in the forehead and says, "Sorry, Sasuke. Maybe next time." But next time he just says the same thing.
Mama pats him on the head.
"He's growing up, dear," she says. "It's only to be expected."
She doesn't point out that Itachi is very busy now, even though Sasuke has noticed that his brother isn't home by nightfall at least once a week. Neither of his parents mention that Itachi is suddenly out on missions all the time. And they don't seem to have noticed that there's something different about him. Sasuke thinks he looks sad all the time: there's a permanent tiny notch between his brows, and his tear-troughs look as deep as Papa's.
Sasuke hugs him when he can and tries to remember funny things that happened at school. It doesn't cure him, but sometimes Itachi smiles.
"Maybe he's got a girlfriend," suggests Shisui-nii when Sasuke asks him why Itachi is out so often - not that he's around much either.
"He does not," says Sasuke furiously. That's an awful thing to say.
"Calm down, calm down." Shisui's blase attitude to Itachi-nii potentially having a girlfriend only upsets Sasuke further. "Hey, I was only teasing you," he says hurriedly when Sasuke's lower lip wobbles. "Really, I'm pretty sure he doesn't have a girlfriend. He's just very busy with missions right now. It's a busy time."
It's true, everyone is busier than usual. But Sasuke gets the feeling there's something he's still not being told.
After Itachi leaves the village, Sasuke falls into a fever for three days. He dreams strange dreams, but can't remember them on waking.
He isn't allowed to return to the compound: they give him an apartment in town instead. It's pristine and anonymous in a comfortable, comforting way. It feels as if this is just a hiatus in his ordinary life with his family. He doesn't go out, so he doesn't have to look people in the face and know that they know.
The night before he's due to return to the Academy, after his bath, he notices something in the mirror he hadn't noticed before. It's a birthmark, orange and raised, in the shape of a stylised lotus leaf, just above his right buttock. By some instinct for the out-of-place, he knows immediately that it's not an ordinary mole.
So he has a soulmark. He doesn't know how he didn't notice it before, but it is somewhere he doesn't tend to look - but why did no-one tell him? He squints at it in the bathroom mirror for a long moment before wrapping himself in a towel. If he'd discovered it a few weeks ago, he'd probably have been excited.
Itachi has a soulmark, he remembers; but he can't recall the shape, just a fuzzy blob. Does that mean that somewhere out there, Itachi will find his soulmate? What could it be like, to meet your soulmate and discover that they'd murdered their whole clan? The girls at school say you'd love your soulmate no matter what they'd done, but Sasuke knows how love can change.
What if Itachi already found his soulmate? Might that be why he left the village? They say you'd do anything for your soulmate: what if that was what they meant?
Sasuke knows he's only making excuses, but that night he dreams of Itachi held in the grip of some shadowy figure, begging to be saved.
"Hey, you've got a soulmark!"
"Go away," Sasuke snaps, fending off Naruto's poke at the mark and wading further into the stream to get away. "And stop looking!"
"But it's cool!" Naruto doggy-paddles towards him, then gives up at the look on Sasuke's face and floats lazily instead. "I haven't got one."
"Well I don't want one." Sasuke sinks briefly under the water to scrub at his hair. It's a hot day in Tea Country, and he feels dusty all over. When he surfaces, Naruto is still staring at him.
"You don't want it?"
"Nope." Sasuke wades towards the bank. "It's a pain." Sometimes literally, waking him in the middle of the night with hot aching like a joint sprain, though he's not going to tell Naruto that.
He can feel Naruto's eyes on him, and he turns to tell him off again for staring - only to find Naruto gazing pensively into the middle distance, hair dripping down his face.
"I'd do anything to have a soulmark," he says.
Embarrassed, Sasuke turns away.
Itachi effortlessly hauls him up off the ground and holds him up against the wall of an inn in Shukuba Town. His hand around Sasuke's throat is fiery hot, almost feverish as it cuts off his air. Sasuke's broken wrist sends shockwaves of pain radiating up his arm and makes his vision blur: Itachi's Sharingan become red smears.
For months, he can't close his eyes without being haunted by the ghost of Itachi's breath on his face and the power in his adult body. The physical memory comes upon him at odd times: training, or just walking down the street. His brother is a man now, and Sasuke is still a boy.
"How interesting," says Orochimaru. Sasuke stands there in his underground rooms with his shirt pulled up and hates him like he's never hated anyone before.
"Your brother had a soulmark too, I recall." I know, what's that got to do with anything, Sasuke wants to ask, but any scraps of information that Orochimaru has on Itachi are valuable to him.
There's a long pause. Orochimaru makes no sound behind him, but Sasuke knows he's there, running his eyes over Sasuke's bare back. He wonders how Orochimaru found out about Itachi's mark, then tries not to think about it.
"Do you know, Sasuke-kun, that by the time I met him he had already found his soulmate? Unusual, in one so young."
Sasuke had no idea. He can't name the emotion he's feeling.
"Who was it?" he asks, trying for an off-hand tone and failing.
"Oh, I couldn't say." Orochimaru's voice recedes as he drifts back to lounge in his armchair. Sasuke lets his shirt fall and wishes for him to drop dead. "But you have met them."
And with that bombshell, he dismisses Sasuke from his chambers. By this stage, Sasuke knows better than to try to cajole more information from him: he exits with his face as flat as he can make it and strides down the corridor towards the training arenas, their sides already singed from Chidori practice.
Somebody he's already met? He wonders whether shark-guy is Itachi's soulmate. It seems fitting, but also somehow not. But who else could it be?
You've already met them. Orochimaru's words haunt him for weeks.
Sasuke has a reliable fantasy:
Itachi is cradling him in his arms. It doesn't matter why, only that he is. Neither of them is wearing any clothes
Sasuke takes his sword and stabs him through the gut, ramming it into his brother's body. Itachi throws his head back and cries out as blood spurts from the wound, face contorted in agony, body shaking and shuddering around Sasuke's.
Sasuke bites his lip as he comes, and he never makes a sound.
Sasuke wakes up and discovers that he no longer has a soulmark.
He also no longer has a brother. It takes Madara to connect the two.
You'd do anything for your soulmate. Everybody knows that.
His eyes are swollen and sore as if he's been crying, but his cheeks are dry. It might just be inflammation from the Mangekyou. The memory of Itachi's soulmark, no longer blurred by genjutsu; the realisation that he had his own all along; the sick knowledge that everyone has lied to him.
He takes the only remnants he has of his brother and lets Madara anaesthetise him for the procedure to implant them - but only enough to take the edge off the pain. He wants to be aware of the moment when Itachi's eyes connect to his nervous system. It's the closest they'll get to a consummation.
"No matter what happens from here on out, I will always love you."
Itachi's forehead is cool against his, hand gently gripping Sasuke's hair. All he can see is Itachi's red and black eyes - the same eyes that Sasuke now sees through. Kabuto is coming to the end of the hand seals to release the technique, and he won't lose a moment.
Sasuke reaches up to cradle his brother's cheek, feeling the fine cracks in the skin, and before Itachi can dissolve into ash or he can lose his nerve — he seizes Itachi's mouth in a kiss. A bolt of lightning riccochets through him; the hairs on his arms stand up.
Beneath his fingers, the spiderweb of cracks heals. Itachi slumps heavily in his arms, making Sasuke strain to catch him.
Kabuto has finished his seals, but Itachi lies whole and breathing in Sasuke's arms.