Itachi is only thirteen and a half when searing pain cuts across his wrist. He stifles his response, managing not to cry out, but tears sting his eyes as fate writes upon his skin. He doesn't look. He can't. He's on a mission, deep in enemy territory, and even a glance at his wrist wouldn't reveal anything. The armour covers the spot where the mark is forming, hiding the burning flesh from sight.
He carries on. He continues with the mission, executing the orders they've been given with deadly precision.
He doesn't dare to look at his wrist, keeping the mark hidden beneath his armour and a discrete layer of supportive bandages. He doesn't want to know. If he sees the tattoo now emblazoned on his skin, he runs the risk of recognising it should he ever see it on his intended soulmate's skin. He can't return with the mark visible. In truth he's afraid of it, and of the whole thing. He knows how powerful the love that binds soulmates can be, and he's not ready for his world to shift like that. He's young for the mark to appear, and has so much left to do to serve the village and his clan before he can allow his priorities to shift. Most people find their mark appearing between the ages of fifteen and eighteen – sometimes older if their soulmate is particularly young. The only thing Itachi can guess from the untimely appearance of his own mark is that his soulmate is a good deal older than him, or, if the stories are to be believed, that the love he and his soulmate have the potential to share is unbreakably strong.
The universe has plans for him he cannot keep to. The mark has to go. He won't even tell Shisui, who he entrusts with everything, about it.
There are two operatives within the ANBU, occupying 'administrative' positions, who can seal the mark. Itachi finds his way to one of them, making sure the rest of his team has gone home. He doesn't want anyone to know. The kunoichi he hands his arm to is sealed against revealing the work she does. She will never tell anyone.
Just a few minutes, a handful of powerful seals and a rush of chakra, and it's done. Itachi looks at his wrist when it's all over. There is nothing there.
.
No one looking would ever know, but Itachi can feel it. He can feel the mark on his skin, itching and tugging, fighting with the seal. The seal is strong, and he can sense it will not break – especially not if he tops it up with his own chakra from time to time – but the sensation is ever-present. Sometimes at night he can't help lying awake, thinking about it. The constant sensation eventually becomes something he can ignore, only feeling when he focuses on it to gauge the strength of the seal. Time passes, and eventually he barely thinks of it at all.
.
Sasuke gets his mark young too. Itachi wonders if it's a family thing, and almost asks his mother about it. He wishes he did. She dies, far too young, choking up volumes of blood Itachi can do nothing to stem. He screams for someone to fetch a medic, but they're too late, and his own attempts to prolong her life are futile. She dies in a bloody heap on the kitchen floor, and a blinding pain tears at Itachi's eyes, his tears crimson as they fall on Mikoto's pale, slack face.
.
At the funeral he struggles to know what to do. His father is mute, Sasuke a volatile ball of rage, and everyone else is solemn and respectful. Itachi is in shock. He goes through the motions, unable to process what has just happened.
Because something more than just his mother's death happened to him. It's something he hasn't told anyone else about. Like the soulmate mark on his arm, he's worried about what it will mean, and what will change. Some concerned relatives have already asked him how he is, in a loaded way that makes him suspect they know what might have happened, but he doesn't tell them. He doesn't confide in them.
There's only one person he trusts enough, but it's another four days after the funeral before he can talk to Shisui. In recent years, the missions they take afford them less time to train or spend time together, but Shisui is still the closest friend Itachi has. He can't imagine that ever changing. It has been fourteen years since they met, and Shisui has been a comforting constant in his life ever since that day.
He's also the only other person Itachi knows who has different eyes.
With Fugaku having thrown himself into work and Sasuke almost always out, no doubt fighting Minato and Kushina's son, both of them angry that the fates have paired them together, Itachi and Shisui could have the house to themselves. Itachi chooses to be elsewhere, though, that morning asking Shisui to meet him at the same place they used to meet when they were younger.
Itachi arrives early, only to find that Shisui is earlier still. From the dampness of his hair and freshness of his clothes, he seems to have come straight there from a post-training shower. Itachi takes a seat next to him, their legs dangling over the edge of the cliff, and he listens to the roar of the waterfall, and the river far below.
"I have the same eyes as you," he announces after a while.
Shisui is silent for a moment, and Itachi senses him bowing his head. "I'm sorry."
He understands, then, what is required to unlock the high level of power Itachi now possesses.
"You never did tell me what it meant."
Shisui had promised to tell him one day, should he ever need to know. He needs to know now, even if he's already worked it out.
"The mangekyou sharingan," Shisui says, naming something legendary amongst their clan. "It comes from witnessing a death of someone whose passing brings you great suffering."
Itachi doesn't ask the next question, but Shisui answers it anyway.
"A team mate of mine fell behind. I was bitter; jealous of him. I failed to reach out and help him. I didn't save him."
It's Itachi's turn to sag under the weight of knowledge. "I'm so sorry, Shisui," he breathes. He'd never known. Shisui had never told him.
They lapse into silence, the rush of water drowning out their thoughts. Itachi isn't sure what else there is to say. His questions seem unimportant.
"I don't want anyone to know," he says at last.
"You're the only one who knows about mine," Shisui admits, his words a promise of secrecy.
"It feels… private." Itachi feels the need to explain himself. He's relieved when Shisui understands.
"Yeah," his friend sighs. "I don't want just anyone to know about it. I do everything I can to avoid using mine too."
Itachi looks round at that, sensing Shisui is talking about a reason other than keeping his sharingan secret. "What do you mean?"
Shisui is solemn as he replies: "This power is gained at such a high cost. It feels like there is a cost for using it too."
"A cost?"
Shisui gazes out over the chasm before them. "Some of the light has left my eyes."
It takes a moment for his words to sink in, and when they do, Itachi stares at him, horrified and feeling a flicker of anguish.
"You're going blind?"
Shisui's attention falls to his knee, and he plucks at his clothes.
Itachi frowns, noticing something else; something he's never seen before.
"What's that?" he asks, staring at a faded smudge on the inside of Shisui's left wrist.
Shisui flinches, hiding it, and then lets out a shaky exhale and exposes it again. It's so customary to see him with wrist guards that Itachi is taken aback by the dirtied expanse of skin.
"It's my soul mark."
It's ugly, and ruined. The blurred, faded mess holds a reluctant, macabre fascination for Itachi, who has only ever seen bold, crisp, clear lines in others' marks.
"What happened to it?"
Shisui gives a pitiful huff of self-depreciating laughter. "My soulmate didn't want me."
Aghast for the second time in as many minutes, Itachi feels the already broken shards of his heart fracture even further, aching unbearably on Shisui's behalf. He doesn't know what to say.
"Shisui…" he begins, wishing he'd known, and could do something.
Shisui shakes his head, dismissing the topic. "Not important," he lies. The tightness in his voice betrays him. "So," he continues, clearing his throat. "Have you tried…?" he gestures up at his own eyes. "Do you know what power she gave you?"
"Not yet," Itachi half lies. He can feel, through some strange instinct, what abilities lie in each eye, but he doesn't want to try. He'll use it one day, if he has to.
He hopes that day never comes.
.
The illness that took his mother's life lies dormant within Itachi's body. Sasuke's too. The revelation, so quick on the heels of Mikoto's death, is terrifying. Itachi can't bear the thought of losing Sasuke too, and Fugaku is clearly distraught by the possibility. Their family, for a time, falls apart.
Itachi's missions lessen. Minato has brought together the other Kage, and a new, solid strategy for peace is starting to come to fruition. Kushina appears in the Uchiha family kitchen almost every other day, cooking and fussing over her friend's widower and grieving children, and Itachi makes a renewed effort to train with Shisui when their schedules allow. He worries his friend will think he's doing so out of pity, and he has fourteen different speeches rehearsed explaining how and why it's his own needs that drive him to do it, but Shisui never asks. He seems more grateful for the regular opportunity to spend time with Itachi than he will admit, so they never mention it.
It's harder not to mention the soul mark, though. Now and then Itachi catches sight of it – when they're changing, if Shisui's cooking at his home for Itachi, when they go to the hot springs together – and he can't help but wonder. He thinks about his own sometimes, wondering if it's cruel to keep whoever his soulmate was supposed to be shut out of his life. He doesn't want any more heartache though – neither in losing them nor being rejected, as Shisui was – and at this point revealing is isn't exactly an option. Everyone thinks he doesn't have a mark. His twentieth birthday is just days away, so they all, mistakenly, think that if it does appear his soulmate will be years younger than him. Little do they know they're looking in the wrong direction. His soulmate, whoever they were, is likely to be almost thirty now. Tired of waiting for someone who never came, they probably moved on with their life and married. Maybe they're dead.
Itachi is better off not knowing. He has enough to contend with, and his father's visceral grief has left Itachi with more to bear than normal. He hasn't taken over, but he feels like he's picking up the pieces his father is dropping in his distraught wake. His parents were soulmates. The marks on their inner wrists were perfect copies. Now, the one on Fugaku's skin is as clear and as sharp as ever, but blood red in colour.
Itachi looks at Shisui's mark and wonders, but holds back his questions.
.
It's a relief to everyone in the village when Sasuke and Naruto eventually to come to terms with the fact they universe has given them a chance to find love together. It's been a long, hard year since Mikoto died, but the family is starting to piece itself back together again, and Itachi catches himself smiling as he sits on a bench and watches his brother and presumably-one-day-bother-in-law walking past the festival stalls, hand in hand, half bickering, half teasing each other over something.
Shisui, by Itachi's side, watches him.
"Do you wish you had a soulmate?"
The question catches him off guard, and Itachi's smile falters.
"I, uh… I try not to think about it," he says, not exactly lying. "There was never a good time in my life for it to happen. Besides," he continues, looking back towards where his brother has disappeared into the crowd. "It's too late now."
He can't decipher the sadness weighing down on Shisui as his friend reaches out and takes his hand. He lets him do it, not questioning Shisui's actions. They're close. Having Shisui reach out to right his clothes or brush his hair back into place is nothing out of the ordinary. The careful attention also reassures Itachi that Shisui's sight hasn't grown any worse since that unwelcome revelation.
"Do you ever think of finding someone else to be with, or are you waiting?"
It takes a moment for Itachi to realise Shisui has asked him something. Shisui has taken his left hand, and Itachi has to make a conscious effort not to flinch as a jolt tears through him at the light, delicate touch of Shisui's finger against the point where the seal hides his mark. He also has to fight the instinct to channel more chakra into the seal. He's grateful that the kunoichi who created it was a Hyuuga, and as such the seal is undetectable to all but the most advanced byakugan users, but he's wary of discovery anyway.
Shisui doesn't seem to notice anything. He's silent, tracing an absentminded, somewhat symmetrical pattern on the inside of Itachi's wrist as he waits for an answer Itachi almost forgot he was supposed to give.
"I hadn't thought about it," he at last responds. "Are you…?"
"Still waiting?" Shisui finishes, his finger tickling the inside of Itachi's wrist. "I don't know." He pulls his hand back, self-conscious in the way he touches the spot where his own ugly blemish of a mark hides. Itachi feels a flicker of hatred and resentment towards whoever it was that turned Shisui down. Shisui would make an amazing partner. Anyone would be lucky to have him.
In a show of solidarity, and uncharacteristic forwardness, he pulls Shisui's hand into his lap. He doodles a pattern over the concealing bandages, realising after a second that he's only tracing Konoha's symbol, and then the Uchiha fan. Still, it seems to soothe Shisui, who leans back with a sigh.
"We should go."
Shisui mumbles his words, sounding tired, and neither of them make any attempt to move. After another few minutes of etching invisible shapes onto Shisui's arm, Itachi sits back too.
"There's no rush," he decides, talking about more than just the festival.
Shisui, understanding him, grunts softly in sad agreement.
.
Later that night Itachi can't help staying up, staring down at his wrist in the dim light of his room. His father is on night shift, and Sasuke at Naruto's, leaving Itachi alone with Shisui, who has long since fallen asleep in the guest room next door. A while ago Itachi thought he'd heard him sobbing, but he'd been polite enough not to go and see.
Now all is quiet, and Itachi is left alone with his thoughts. They're mostly absent, leaving him with the impulse to lift the seal and see what's beneath it, no matter how ill-advised that course of action might be. His conversation with Shisui has him thinking. He wonders if it really is too late. Is his soulmate still out there, waiting? Would they still want him, and accept him? How would he explain so many years spent hiding from what the mark could mean?
As he often does, he thinks of his mother. He wonders what her advice would have been, had she known. Something kind-hearted and optimistic, no doubt. He still wishes he'd been able to ask her so many things, and say so many more.
Looking at the blank skin of his wrist again, Itachi tries to reason with himself. His head doesn't cooperate as he thinks it should, offering little to dissuade his heart. He's curious. He shouldn't be. There's no reason to be. He made his decision years ago, after all.
But so much can change, even in an instant. He thinks of his mother again, and then decides he wants to know. He wants to see. After that, he can decide again. He can always return to ANBU to have it re-sealed, if he wishes. Hell, the mark might even be a distorted, hideous inky bruise as Shisui's is, or blood red like his father's.
There's only one way to find out.
It's easy to drain the chakra from the seal, it having been designed to respond to his and the kunoichi's chakra. Something within Itachi shivers in anticipation, but he ignores it, focusing on undoing the complex binding that keeps his skin blank. He can feel the itch beneath it, the soul mark almost struggling to be free.
In hindsight, Itachi knows he should have expected it, but he wasn't ready for the pain. It felt just as bad as the day the mark appeared, and he fights back a cry, blood roaring in his ears and hands fisting in the sheets as pain tears across delicate skin. Distantly, he hears a muffled cry and a thump, but before he can register anything more he blinks once, twice… and then stares at the vivid black mark on his skin.
His blood stills. Something very powerful and raw grips him as he looks down at the unique shape on his skin: the shape only he and one other person in the world share.
He recognises it.
It's the shape of a mangekyou sharingan. More specifically, it's the shape of his sharingan and Shisui's, combined. Two drawn into one, seven spokes of one wheel.
Shisui.
He's moving before he can think twice about it, darting from his room and tearing open the door to the guest room. Shisui, having turned on the bedside lamp, sits in a pool of blankets, staring down at his arm.
His face, when he looks up, is one of disbelief, and anguish.
"You," he breathes, the word brimming with pain. Tears well up in his eyes that have nothing to do with the pain Itachi knows he felt too. After all, what else would have woken him at the exact moment Itachi released the seal?
Caught by Shisui's tone, Itachi stands, frozen in the doorway. He'd thought to rush to Shisui, but the action seems stupid now.
"I… I thought…" he stammers, gaze falling to Shisui's arm. The mark, as he'd knew it would be, is identical to his own. He has the overwhelming urge to move forward and touch it, confirming that it's really there. Some distant, detached part of his mind still clings to what it thought it knew. "But your soulmate rejected you."
"You did," Shisui breathes.
The pain is too much to bear, and Itachi grasps at the doorframe for support. "I… I was thirteen… I was scared of what it meant."
"And I was so damn happy!"
Tears fracture Itachi's vision, but not enough to prevent him from seeing those that spill over Shisui's cheeks.
"I was so happy," Shisui whispers. "I couldn't wait to meet you."
He pauses, shivering, and Itachi tries to work out what to do.
"And then you… They say that when your soulmate destroys their mark, when they don't want you…"
Shisui's words break off, and Itachi forces himself to remain where he is, ignoring the desperate longing to go to Shisui.
"I'm sorry, Shisui," he says. "I'm so, so sorry."
"I thought you didn't want me."
"I do, though," Itachi insists, his voice soft even in his earnestness. He realises that he would have wanted Shisui then too, even if they were young teenagers, their lives already devoted to their clan and the village. "I do."
The doorway isn't a suitable place for this conversation to continue, but Itachi doesn't feel comfortable inviting himself into the room. Taking a deep breath to steady himself, he asks: "Would you like to meet me now?"
The shift from pained dejection to tentative hope lifts his heart, and Itachi barely waits to hear Shisui's "yes, oh gods, yes", before moving towards him. They meet in a tangle of limbs, Itachi falling and being pulled down, his lips meeting Shisui's as they crash down onto the bed. He's never thought about kissing before, and never cared to consider it, but now it's all he can think to do as he locks his arms tight around Shisui, and finds himself held in return.
Breathless, elated, and fearful, they break apart, trembling. It occurs to Itachi that he's just kissed Shisui – his closest friend and distant clan member – but that doesn't sound right, so he does it again, just to make sure. Shisui's cheeks are damp, quickly drying tears salty against his lips when he pulls away to kiss them from Shisui's skin. He hates that they were ever there.
"Itachi," Shisui murmurs, hands now stroking Itachi's hair. "'Tachi…"
"I'm here," Itachi promises, sealing it with a fleeting kiss and then continuing his worship of Shisui's skin.
The sound of Shisui laughing is the most beautiful thing he's ever heard, and he doesn't know what's caused it, but he doesn't much care. It's only when Shisui begins to sound a little delirious that he stops, loosening his fierce grip on Shisui – on his soulmate – just a little.
"What? What is it?"
Shisui smiles, and strokes Itachi's face and leans in to kiss him as his hand reaches for Itachi's arm. He thumbs the mark, and then looks down at it, confirming it's there.
"I've spent so long wishing it could be you," he admits. "I wondered if you were waiting, if your mark would appear, and if you'd take a reject like me if you ever chose someone."
"Of course I wou—"
Shisui silences him with a kiss, pressing bodily against him. Itachi can feel the longing and desperation within him; he feels it too.
"How did you know, though?" Shisui asks when he pulls away. "What made you realise it was me?"
It feels better to demonstrate on Shisui's skin. Itachi guides Shisui's arm into the space between their chests and looks down, fingers tracing over part of the beautiful mark that has solidified in Shisui's skin.
"Your mangekyou," he explains, shifting his attention to the remainder of the pattern. "And mine."
Shisui's breath catches audibly, and it's another few moments before he speaks again. "Are you going to hide it again?"
"No."
That's not even a question, although he can kind of understand why Shisui asks it.
"What are we going to tell everyone? They won't believe it appeared at our age."
"Stranger things have happened," he points out. It's a better use of their time to kiss, so they do, Shisui pushing and rolling Itachi onto his back. Itachi goes gladly, finding himself a little too close to the edge of the bed, and not near enough to Shisui.
Stranger things have happened, indeed, but even if they hadn't, no one is going to challenge them. The mark they both share is proof that, no matter how it got there, the universe has earmarked them for each other, and given them the chance to experience all the love and happiness sharing you life with a soulmate can bring.