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There is a strange phenomenon in which two people with compatible chakra will react strongly to each other when in physical proximity. No one is sure what triggers the alignment, but the effect on the involved parties is as sudden as it is visceral. Sometimes it happens upon first meeting, others after having already been acquainted for some time.
Iruka and Kakashi have been navigating an uneasy truce for a while when they feel the tug deep down in their guts, a flash fire that leaves Iruka dazed after Kakashi hands in his report and leaves the Mission Room one evening, seemingly unaffected. Iruka’s flush, however, is obvious. The other shinobi on duty gives him a worried look and suggests he go home early, mentions how it’s the flu season and Iruka’s job at the Academy probably means he caught it from one of the kids.
Usually, Iruka would argue. He would say he’s all right and finish his shift. Now, all he can think about is Kakashi and how pale his skin is and how much Iruka wants to see all of it so he can press his palms to Kakashi’s ribs and map out his heartbeat. So, Iruka nods, gathers his things, and heads home four hours earlier than he normally would.
When he gets there, Kakashi is perched on his balcony.
“Good evening, sensei,” he says.
His voice sounds deeper than usual, richer, not a trace of his usual indolence or insolence in it. He’s focused, perhaps even eager, and he doesn’t seem the least bit put out by the fact that his chakra pathways appear to have aligned overnight with that of a chūnin Academy instructor who makes a habit of scolding him as though he were one of his pre-genin students.
Iruka gestures at Kakashi to join him at the front door, and the man does just as Iruka digs out the key to his place from his back pouch.
“Personal items in your mission gear?” Kakashi asks.
“I don’t know if you’ve noticed, Kakashi-san, but I don’t even go on missions,” Iruka replies, then unlocks the entrance to his home and pushes it open. “Please come in. We need to talk.”
Kakashi makes a sound of agreement, then crowds Iruka against the door the moment it clicks shut behind them. Iruka isn’t sure when it happened, but Kakashi’s mask is down and his mouth is on his, warm and demanding. Iruka freezes for one long second before he reacts and rakes his fingers down Kakashi’s back, his nails catching on the embossed red whirlpool as he drags his hands down.
The low groan Kakashi gives in response shoots straight through Iruka’s groin. He feels faint, an undercurrent of static tickling his chest in the area where he knows his anahata lies. His heart is hammering wildly against its cage, and Iruka breaks the kiss when it all becomes too much. They haven’t done anything except cling to one another, but he’s still panting as though he’s just finished running ten laps around the village.
Kakashi is faring no better, leaving a trail of breathless kisses down Iruka’s throat. He unzips Iruka’s vest and pushes it off his shoulders, letting it fall to the ground. Iruka tries to do the same with Kakashi’s own, but his hands are shaking too much to do anything more specific than grope at Kakashi’s clothes and tug at them in silent request. Kakashi unzips his vest but doesn’t take it off, instead untucking Iruka’s shirt and sliding a hand up his belly. His touch against Iruka’s skin is soft electricity, raising goosebumps wherever it goes.
Iruka cups Kakashi’s face with one hand and reels him back in for another kiss, using his other hand to reach down and feel Kakashi through his slacks. Kakashi gasps and grinds against his palm, nipping Iruka’s lower lip before proceeding to do very filthy things with his tongue to Iruka’s mouth. Kakashi’s hand is on his chest now, right over his anahata, and Iruka almost sobs at how good such an innocent touch feels, how much better it is than their heated kiss or Kakashi’s erection against his palm or his own hardness against Kakashi’s hip.
Iruka’s hands leave what they’re doing and slide under Kakashi’s shirt—already untucked—and press against Kakashi’s chest. Kakashi is the one who sobs then, a small broken hiccup that makes him jerk back and stare at Iruka, his single eye wide and bright. Iruka’s hands aren’t tingling here—they’re burning. It should be unbearable, but he would rather die than pull away.
Kakashi opens his mouth to say something—thin lips, beauty mark—but then shuts his mouth and removes his vest instead. His shirt follows right after, leaving him standing bare-chested in Iruka’s genkan, his pale skin a stark contrast to Iruka’s browned hands. Iruka slides them from the centre of Kakashi’s chest to just below his pectorals, and he spreads his fingers so he can encompass as much of Kakashi’s ribcage as he can.
He feels the heartbeat thrumming there, a glorious staccato that tastes like home in a way that nothing else ever has. This is Kakashi’s heart, Kakashi’s anahata, Kakashi’s main tenketsu.
And it’s all Iruka’s.
Chakra alignment is a causality dilemma. For years, people have wondered what comes first: the chicken or the egg? Or rather, the emotional or the physical? Iruka isn’t sure, and he’s recently become aligned himself. Some people claim to have fallen in love or grown to trust one another before the alignment, others to have sparred or embraced or touched in some way, and a few claim newfound physical attraction to have triggered the change.
When Iruka thinks back on the days predating his alignment to Kakashi, he only remembers a polite sort of awkwardness as they tried to become acquainted, to understand, to see what Naruto saw in the other. Iruka doubts that’s enough to align two people’s chakra pathways. For his part, he remembers having made no progress whatsoever. The more he tried, the more he found Kakashi to be an infuriating mixture of pedantic and torpid that may someday drive Iruka to drink. There was no shift in Iruka’s emotions previous to the alignment, not to mention that Kakashi and he certainly never touched, and Iruka’s thoughts regarding Kakashi’s body didn’t change either. Indeed, Iruka’s opinion of Kakashi remains almost virtually unchanged.
So, while people ask what comes first, Iruka asks, Why did it come at all?
The problem is: Iruka doesn’t like Kakashi. He respects and admires him, appreciates everything the man does for their village and wishes he could be half the shinobi Kakashi is, but he doesn’t like him. This doesn’t automatically mean that Iruka dislikes Kakashi, but he certainly wouldn’t suggest that they grab a beer or have lunch together, not as acquaintances, not as friends, and not even as aligned.
Once upon a time, he might have thought Kakashi felt the same way. Kakashi, however, has been acting like Iruka hung the moon ever since their chakras lined up. He’s still annoying, still condescending and prone to looking down on Iruka at times, but now he will stand way too close to Iruka in public and try to sneak kisses when Iruka is stuck filing reports at midnight in the bowels of the Mission Room’s archives.
Much to Iruka’s infinite chagrin, he often lets Kakashi sneak much more than kisses.
Right now, he’s got his back against a bookcase, knuckles pressed to his lips as he tries to stay quiet while Kakashi’s mouth plants a bruise on his neck—right below the line of the regulation turtleneck. Iruka wriggles a little, attempting to communicate the need to stop before anyone walks in on them. Kakashi hums and sucks harder, almost like he’s trying to get at the pulse thrumming in Iruka’s throat, sink his teeth into it as though it were a ripe plum.
Iruka uses the hand not muffling his groans to scratch at the nape of Kakashi’s neck. His chest is burning. In the few weeks since their chakras aligned, the scalding heat that unfurls from his heart whenever Kakashi touches him has become familiar. It has, in fact, become welcome. There was a time when Iruka didn’t experience it, and it wasn’t all that long ago, but now he can’t imagine existing without the sudden flare.
He makes a small surprised sound when Kakashi jerks back, lips wet and face flushed, his single eye dark and unfocused as his breath comes up in short pants. After a moment, Kakashi wipes Iruka’s neck dry with a hand, the texture of his glove’s tough material made soft from extensive use.
“What’s got into you?” Iruka asks, and his voice barely trembles.
Kakashi wipes his mouth, then presses a close-lipped kiss to the spot he’s just finished abusing. “Mission,” Kakashi murmurs against the tender skin, then kisses it again. “Just thought I’d say bye.”
“What, you’re leaving now?” Iruka asks.
Kakashi makes a noncommittal sound, the small vibrations tickling Iruka’s throat. There is a very real possibility that Kakashi isn’t allowed to divulge specific information about his mission. He may not even be allowed to mention he has a mission at all but has decided to tell Iruka anyway. Why? Less than a month ago, he wouldn’t have. Now, Kakashi trusts Iruka with his life, and that knowledge sometimes knocks the wind out of him. All because they’re aligned. It’s frightening, and it always makes the good burn in his chest turn suffocating.
Iruka pushes at Kakashi’s chest with barely any strength at all, but Kakashi promptly moves back. He looks a handsome mess, and Iruka knows he must be just as dishevelled, if not quite as appealing. He reaches over and pulls Kakashi’s mask up—a clear sign that Iruka is done letting him persuade him into doing things they shouldn’t in locations they mustn’t. Kakashi accepts the quiet command, hitching the mask a bit further up his nose and giving another step back. Iruka’s chest cools down with the increasing distance between their bodies, a hearth fire left unattended, and he suppresses a shiver at how cold the archives seem all of a sudden.
“I’ll walk you home,” Kakashi says.
“No,” Iruka blurts, then amends, “Ah, it’s just—there’s still some filing left to do.”
If Kakashi is disappointed, he doesn’t show it. He reaches up and tweaks the tip of Iruka’s nose. It’s such a far cry from what they were just doing, yet still so achingly intimate. Iruka’s cheeks grow hot, the receding heat in his chest shifting to his face. He grumbles and rubs his nose, well aware that Kakashi is cataloguing every small thing about his reaction for future reference.
“All right, sensei,” Kakashi says. “I’ll get out of your hair now, then.”
“Yeah, okay,” Iruka mutters. He shifts his weight and glances around, hating the fact that he can feel his blush spreading over to his neck and ears. After a moment, he says, “Be safe.”
Eye crinkling up, Kakashi replies, “You, too.”
Kakashi smooths a hand over Iruka’s hair before leaving, his gait unhurried as he exits the archives. Iruka watches him disappear up the stairs, then redoes his ponytail with choppy movements. He feels keyed up, caged despite the fact that he’s no longer being pressed up against the bookcase by Kakashi’s warm weight. He flexes his fingers again and again, trying to dispel some of the energy that has flooded him without warning.
It’s not that he’s aroused. He knows how to take care of that. Using his chakra flow to redirect his blood flow is something all shinobi learn as pre-genin and perfect as they grow up. This restlessness—it runs deeper. He can’t get at it, no matter how many times he presses his hands to his anahata and tries to will it away. It won’t leave him, and he’s not sure if he wants it to.
He rests two fingers over the place Kakashi did a thorough job of marking just now. It throbs a little, and Iruka grimaces when he hides it under the high collar of his shirt. The skin is irritated and unappreciative of the friction, no matter how light. Iruka will no doubt be sporting a purple bruise for a week unless he sees a medic-nin about it.
He will not be seeing a medic-nin about it.
An alignment must be registered for medical and security reasons. The sooner it’s done, the better. In Kakashi’s case, however, it must be kept secret. Iruka doesn’t get a say in it, but he doesn’t resent it—he knows Kakashi doesn’t, either. It’s a secret, and it’s theirs, and though it’s a small comfort, it’s better than nothing. Iruka suspects Kakashi may have confided in someone he trusts, someone close, like Maito or maybe Shiranui, but Kakashi is honest in his denial when Iruka asks. Kakashi could be lying, of course, but Iruka presses a hand to Kakashi’s chest and finds no deceit in the steady warmth that radiates under his palm.
Iruka nods, pulling his hand away. “I believe you.”
“I wouldn’t lie to you,” Kakashi replies. “You can tell Anko if you’d like.”
Iruka looks away, feeling shrivelled up and cold. “I won’t.”
He’s ashamed that Kakashi can see his doubt in him so clearly, his struggles with such tight-lipped secrecy, but this is still new. They’re still learning each other’s edges, snagging on them when they aren’t careful, mending each other’s tears with contrite hands. And Iruka’s been hurt, he’s been betrayed, and he knows Kakashi has lived those experiences too, but Iruka sometimes thinks the weight of it will simply crush him. He’s not strong enough to brush it off, or accept it, or not let it be like splinters burrowed under his skin. Iruka sometimes—too often—thinks that his own heart has betrayed him, time and time again, by opening its doors and letting people in who should’ve been left begging for alms at its steps.
Kakashi isn’t in Iruka’s heart. He frustrates Iruka, and Iruka frustrates him right back sometimes (and takes pride in it); and on some of the nights when they share a bed, they sleep facing away from each other, but their chests are still warm.
Kakashi is in Iruka’s anahata, but he isn’t in Iruka’s heart.
(Not yet, says a frightened, hopeful voice in Iruka’s mind.)
“Have you ever wondered why we aligned?” Iruka asks.
Across the kotatsu, Kakashi stops reading Icha Icha and tilts his head in thought. He gives a low hum to show that he really is giving his reply all its due consideration (Iruka tends to get annoyed with Kakashi if he replies too fast, genius or not), then says, “Naruto.”
Iruka frowns. “Really?”
Kakashi seems surprised by Iruka’s reaction. “Don’t you think so?”
There is some merit to it, Iruka has to admit. Whenever he thinks about the circumstances previous to their alignment, he tends to find that they feature Naruto. Iruka and Kakashi stopped having a not-so-quiet battle of wills whenever they crossed paths, judging each other for their almost diametrically opposite approaches to mentoring the blond boy, only after they had realised that it was making Naruto miserable. That, as far as Iruka can tell, was the only change that could’ve brought about the alignment of their chakras.
“It could be,” Iruka concedes. “But I thought the trigger had to come from us.”
“Didn’t it?” Kakashi asks, tilting his head to the other side.
Iruka breathes out slowly through his nose. “Well, we sure didn’t decide to start acting civil for our sake. We did it for his.”
Kakashi goes back to his book, flips a page. “We also started fighting because of him.”
Iruka’s frown returns, but for a different reason this time. “We never fought.”
“Fine, we quarrelled, argued, squabbled.”
“We just… didn’t agree on things.”
Kakashi’s expression turns amused, eyes still on his book. “Loudly.”
“Mostly me,” Iruka says, then blushes and looks down at the homework he’s supposed to be grading when Kakashi blinks up at him, as though he hadn’t been expecting Iruka to admit that he did most of the yelling back then. In all honesty, he still does. His chest isn’t cold, but it’s not warm either. It just aches. “I don’t want to be aligned to you because we argue.”
He hears Kakashi set his book down softly, then Kakashi’s hands, pale and gloveless in the safety of Iruka’s living room, reach across the kotatsu until they envelop Iruka’s closed fists.
“You’re missing the point,” Kakashi murmurs, and Iruka wants to be mad because that’s the natural response to Kakashi wanting to correct him, but the gaping ache in his chest just widens—and then it up and closes in a cauterising flare of warmth when Kakashi says, “We’re aligned because we’re family.”
That first night, after they were done exploring each other, Iruka and Kakashi lay in bed for hours, ghosting fingers over old scars, pressing kisses to fresh love-bites, holding each other chest-to-chest and feeling the warmth. Iruka sometimes thinks about Kakashi’s palms resting against the long line left by a fuma shuriken between Iruka’s shoulder blades. Mostly, though, he thinks about the silence.
He’s had people comment on it—the mark left behind by a trusted friend, a known traitor. Almost no one ever mentions why Iruka got the scar, and if they do, they get it wrong: he wasn’t fighting a foe, he was protecting his student. That, more than Mizuki’s betrayal, more than the physical reminder of it, is why Iruka would rather no one ever say anything about it to him ever again.
Upon seeing the scar on that first night, Kakashi had said nothing, and he still has said nothing, not in a way that can be heard. He brushes over the healed wound with his hands or his lips sometimes, he ruffles Naruto’s hair and gets him vegetables often, and those are his only comments on the matter.
Kakashi never says anything. Not with words.
Iruka melts a little more in his arms with every passing day.