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The Boy in the Church ⛪

Summary:

They meet in a ruined church on days when lightning splits the sky—Xanxus and the boy with one visible eye, as elusive as mist.

Notes:

Written for KHR Rare Pair Week 2025 — Day 4: Lightning Day / Childhood Friends AU

 

 

Thank you Jo for the pairing prompt! Hope you enjoy it as much as I did writing it 💙

Even though Xanxus and Mukuro are two of my favorite characters individually, they have so few canon interactions that I never would’ve naturally thought to write them, let alone in a childhood AU, which I honestly only picked because I’d run out of other prompts to assign 😅 Turns out, I got really attached to this setup, and now this might be one of my favorite pieces I’ve written.

That said, it’s not exactly a typical childhood AU... I guess these two aren’t built for typicalness, ahah. Hopefully that doesn’t count as cheating! 🫣

(See the end of the work for more notes.)

Work Text:

The first time Xanxus sees the church, he thinks it’s just another broken thing, like his half-mad mother or the holes in his tattered coat.

Perched on the hillside, lightning flashes over its stone bones jutting through the overgrown grass, the steeple strangled in a chokehold of climbing vines. Xanxus has gone farther than usual today, beyond the orchard, past the olive grove where the dogs don’t patrol. He’s twelve, thirteen at most. Doesn’t matter. Not like anyone’s counting.

The thunder starts as Xanxus runs.

Inside, the church smells of moldy soil and ash. Rain pelts through the fractured stained glass, and light fractures over the pews like scars stretched across flesh. Xanxus thinks he’s alone, until a voice says:

“You’re bleeding.”

Xanxus freezes.

There’s a boy on the altar. Barefoot, with messy midnight-blue hair sticking out at strange angles. He’s very young-looking, definitely much younger than Xanxus. Maybe six years old, or less? There’s something in the way he speaks and looks at, or through, Xanxus that feels older, almost adult. A bandage covers his right eye; the left one is blue, with a strange glint Xanxus doesn’t like.

Is he seeing a ghost, Xanxus wonders? He can handle ghosts; it’s people who’ve always been the problem.

And so Xanxus doesn’t bother to answer, though he does drag the back of his hand across his temple. It comes away sticky with blood, probably from earlier, when the store owner he’d stolen a loaf of bread from threw an ashtray at him. He hadn’t even noticed it broke the skin.

“You’re not from around here,” the boy says.

“Neither are you.”

A smirk. “You got me.”

They don’t exchange names that first time. Don’t talk much at all, just wait out the storm in silence. Lightning comes in bursts, illuminating the dusklit church in sudden flashes. Once the storm lets up, Xanxus stands, throws one look back, and walks out. The boy only smiles, saying nothing.

Xanxus doesn’t know why he returns to the church the next time lightning splits the sky. Instinct, a gut feeling. In any case, the boy is there again when he shoves open the warped doors and stomps the sodden mud from his boots.

Moving deeper into the building until he’s a few feet from the boy, Xanxus says with a scowl, “You live here?”

“Not here in the church,” the boy replies with a small, amused smile. “More like... around this area.” His voice carries that same too-grown up tone for a body so young. He grins lopsidedly and adds, “I’m not supposed to be out at all, but when the weather’s bad like this, it’s easier to slip away a bit.”

The boy looks paler than last time. His clothes hang off him differently, like someone yanked them off and stitched them back on wrong. The same bandage covers his left eye.

I’m not supposed to be out at all,” Xanxus mocks the boy’s characteristic inflection under his breath. “Bet you think that makes you cool.”

There’s a chuckle, and the boy tilts his head. “My name’s Mukuro.”

Xanxus doesn’t give his back. Instead, he steps forward and drops down beside the boy on one of the church’s stone steps.

“Weird fucking name.”

“You think?” Mukuro replies, easily. “It’s not my real one. I don’t know if I ever had one. If I did, they took it away.”

They? Xanxus wants to ask. Before he can, Mukuro lifts the sleeves of his worn white tunic.

Lightning strikes, flashing in shards across the stained glass, casting streaks of red and blue over thin arms marked by uneven brands, crooked stitches, and punctures that make the boy look like a ragdoll.

“What the hell—”

“Science,” Mukuro cuts in, replying to what was more expletive than question, grinning. “The future of the Mafia.”

Xanxus looks away. The Mafia...? Like, those big-shot families his mother screams about when she’s all fevered and wild-eyed? He wants to tell the boy it’s not funny, there’s nothing worth grinning about. He doesn’t. He shifts where he stands, jaw clenched, as the motion tugs at the bandages wrapped tight around the tender skin under his own shirt.

That single visible blue eye flicks toward Xanxus’s torso. “Your turn.”

“No.”

“You’ve been walking crooked since you got here. Your ribs—”

“I said no.”

Mukuro doesn’t push, and Xanxus hates him for that too. He’d rather be yelled at, mocked, insulted, or doubted than ever be pitied.

They keep coming back to the church wherever the sky flashes with lightning.

Sometimes Mukuro talks nonsense about souls, reincarnation, the cycles of hell. Xanxus doesn’t get any of it, though hell feels familiar enough. Nevertheless, he listens, mostly in silence, occasionally throwing in a rude, offhand comment.

One time, Mukuro cups his tiny hands together and, to Xanxus’s surprise, a small vine begins to bud and rise from the center: thin, alive, eerily similar to the ones that coil around the church steeple.

Another person might freak out, finally convinced the kid’s indeed a ghost. Xanxus isn’t another person, and the thought of showing Mukuro his flames crosses his mind, though he pushes it away almost as quickly. Sharing is dangerous, trusting even worse; anyway, something about Mukuro makes him think he already knows.

“Do you like it?” Mukuro asks, dragging Xanxus’s attention back to the vine on his palms.

Xanxus shrugs, eyes on the sprout. “Cheap magic trick,” he scoffs.

Looking from Xanxus’s eyes back to his palms, Mukuro is quiet before saying, “It’s my power, the illusions... That’s what they’re after. They think if they control that, they can turn me into a weapon.”

A pause.

“Fuck them,” Xanxus says. “If you’ve got a power like that, you should just kill them all and be free of it.” He’s pretty proud of that solution. When he glances at Mukuro, the boy is smiling.

“You’re right,” Mukuro says, casually. “I should. I’m too weak now, but when I’m grown, I’ll be strong enough to make them regret everything they did to me and to the other kids.”

Xanxus didn’t know there were other kids; that part makes him want to hit something. “A weakass shrimp like you?” he retorts. “I’d sooner bet on a stray dog.” It’s a lie. He can sense that Mukuro’s strong, or will be. It’s not like he’s about to admit it out loud, though.

Mukuro grins again, like the insults are funny or endearing. “Then we’ll wait until we’re both adults. I’ll show you how strong I’ve gotten, and we’ll see who ends up on top.”

When they’re both adults. Xanxus turns the words over in his head. He can’t picture the future at all, not for himself, not for Mukuro. Doubts either of them will make it that far, let alone get anything good out of life if they do.

“Whatever,” Xanxus grumbles instead, swallowing his thoughts. No point beating a dead horse. “I’d like to see you try.”

Another time, Mukuro approaches Xanxus on the pew, dragging a worn cloth bag behind him. He pulls something out and holds it up in both hands like it’s an offering.

A loaf of bread.

“For you,” the boy says. “I took it from the rations at the lab.”

“Keep your goddamn food to yourself, you shrimp. I don’t need your help to eat.”

Mukuro blinks up at Xanxus. “Your stomach’s always growling,” he says, matter-of-factly. “And you’re kinda short for your age. Probably malnourished.”

If the brat weren’t the size of a housecat, Xanxus might’ve punched him.

“There,” Xanxus snaps, yanking the bread, ripping it in half, and shoving a piece at Mukuro’s face. “Happy now? Eat your damn share before you piss me off, you scrawny little lab rat.”

It’s sometime after that conversation when Xanxus returns to the church, soaked and shaking, blood seeping through his sleeve from a knife wound. One of the shopkeeper’s relatives had caught him, called him a thief, the son of a mad whore, and slashed at him. Xanxus lit his flame and smashed the man’s face in. That sent the town into a frenzy, chasing him off with shouts and stones.

Afterwards, his mother had gone hysterical, screaming that she’d take Xanxus to Vongola Nono, that Xanxus was the heir to that great and powerful family. She had run out of the wooden shack they called their house and into the pouring rain, raising her fist to the thundering skies with an exaggerated flourish ripped straight from one of those traveling puppet shows Xanxus had watched as a kid, shrieking that the village would regret everything once they realized her son was the chosen one.

Xanxus is feeling sick to his stomach as he pushes the church door open, expecting that annoying grin, the strange stories, and the offbeat jokes he’s come to rely on to keep his mind off everything else.

Mukuro isn’t there.

The pews are empty, so is the altar.

Xanxus sits. Waits.

When the storm ends, Xanxus leaves. Mukuro isn’t there the next time, or the time after that, or the time after that either. And Xanxus does everything in his power to thrust the sinking feeling in his gut down into the bottomless cavern of his rotten heart.

The last time Xanxus goes to the church, he walks out and descends the hill without once looking back. He should’ve known better than to expect anything. Even on the days of lightning when they met, the boy had always been as elusive as mist.

*

Shortly after, Xanxus’s mother gives him away. More accurately, she hands him off like a scalding burden into the hands of Timoteo, the Vongola Nono, who looks him in the eye and calls him his legitimate son.

Now he has three older brothers: Enrico, Federico, and Massimo. They’re smug, two-faced twats, and Xanxus hates every one of them.

Xanxus might’ve come from nothing, but he’s not useless like them. Maybe his mother wasn’t crazy after all. Maybe she was right. Maybe Xanxus really is meant to be Vongola Decimo.

For the first time in his life, Xanxus feels worthy. His existence has direction, an endgame beyond wasting away the days.

Then, of course, Xanxus finds the papers—the ones that say Xanxus isn’t Timoteo’s blood. He was never a legitimate heir, never part of the succession. And just like that, he’s back where he started, with the added humiliation of being a charity case, adopted out of pity.

It flips Xanxus’s world upside down. No way is he going to let that stop him; not after everything he’s been through.

At sixteen, Xanxus meets a lunatic named Superbia Squalo who hands him command of the Varia on a silver platter. Xanxus takes it. The timing feels right. The Vongola name, the bloodline, the throne: it all should have been his from the start.

So Xanxus makes his move.

It goes horribly wrong.

In the moments before he blacks out, frozen mid-breath by Timoteo’s Zero Point Breakthrough, all Xanxus can feel is pain, and he’s relieved that that’s the last thing he’ll feel before he dies. He doesn’t need his depressing fucking life flashing before his eyes or any of that crap.

Though apparently, it doesn’t matter what Xanxus needs.

As if on cue, like the universe couldn’t resist one final joke at his expense, a ruined old church flashes through Xanxus’s mind, along with a boy he hasn’t thought about in years, and the stupid, ugly truth hits him: he had been happiest there.

*

Cold is the first thing Xanxus feels when he comes to.

A cold sunk deep into him, down to the bone. His limbs won’t move. His breath is jagged. It’s like his body forgot how to function.

There are hands on him. One under his shoulders, another at his side. He’s being dragged.

Sound bleeds in slowly. Voices; three, maybe. Low and muffled—Xanxus can’t make out the words. 

Through the fog, one of the voices stands out, slipping into Xanxus’s awareness, a strangely familiar fragment from some long-lost dream.

“Ken, Chikusa... watch his arm... no, keep his head up... his breathing’s shallow...”

Xanxus tries to lift his head. Tries to open his mouth. Nothing moves. His pulse thuds in his ears, slower now. His vision tunnels.

The cold creeps higher.

The voices fade like they’re slipping underwater.

And then—

Nothing.

*

When he wakes again, Xanxus is in bed. At least, he thinks it’s a bed. Soft sheets beneath him, something like a pillow under his head. In any case, he’s mostly too sick with nausea to think much at all.

Lightning splits the sky outside; he can see it through the half-drawn curtains and hear the rain drumming against the glass. It’s warm in the room, so maybe it’s spring, maybe summer. Or Xanxus’s so cold inside that everything will feel warm from now on.

“You’re awake at last,” says a voice to his side. “Good. I was beginning to get a little worried, you know.”

Xanxus drags his gaze over, and there he is. It’s Mukuro. Recognizable, yes. Only, he’s a lot taller and broader than when Xanxus last saw him. His features have shifted from those of a child to the sharp, handsome face of an adult. One thing stands out immediately: in addition to the blue left eye, there’s now a supernatural-looking red one on the right, etched with a character Xanxus vaguely recognizes as Chinese or Japanese, though he has no idea what it means.

Another thing that stands out is the absence of the horror show Mukuro’s arms used to be. What’s visible, beneath the rolled-up sleeves of his white shirt, unbuttoned low at the collar, is perfectly unmarred pale skin.

All in all, somehow, Mukuro looks even more unreal than he did all those years ago. It actually makes Xanxus wonder if he’s hallucinating on his deathbed.

“Where... am I?” Xanxus hears his own voice, hoarse and cracked from lack of use. “Why the fuck are you here?”

The musical laugh that echoes through the room and cuts through Xanxus’s haze is vivid enough to make him suspect he might not be hallucinating or dead, after all.

“Is that really how you greet your childhood friend?” Mukuro says as he steps closer, settling into a chair conveniently placed beside the bed.

Though he’s scowling, Xanxus is starting to feel a little less dazed and nauseous. “When... did you get so damn tall...?”

Mukuro smiles. “I could ask you the same. I suppose the Vongola fed you well, at least.”

The mention of the Vongola leaves a bitter taste in Xanxus’s mouth. He shifts, grits his teeth, and pushes himself up on his elbows. That’s when he notices he’s naked beneath the sheets. His body feels off. Bigger in some places. Heavier. There are scars across his chest and arms, dark and unfamiliar.

“To answer your questions,” Mukuro says, and Xanxus forces his gaze away from his body and back to the boy, no, the man before him. “You’re in one of my hideouts. It’s been about ten years since Vongola Nono froze you. I’ve been looking for you ever since I got out of the Estraneo lab... Took me a while to realize you were the fourth of Timoteo’s sons.”

One of Mukuro’s hands lifts from his lap. It reaches out slowly, brushing his fingers along Xanxus’s jaw, thumb gliding over his chin, his lips.

“You never did give me your name, Xanxus,” Mukuro says, softly. “Once I figured it out, I infiltrated the Vongola. Took some time, but I learned how to undo the Zero Point Breakthrough with my powers.” He smiles, satisfied. “Not exactly a simple trick to pull off, so I trust you’ll have something flattering to say once you’re back on your feet.”

The explanation runs through Xanxus’s head—especially the part about Mukuro being able to undo the Zero Point Breakthrough; honestly, he’s impressed by how strong Mukuro must’ve gotten based on that alone—but his brain short-circuits at one part in particular.

Ten years.

A fucking decade?

He’s been on ice for a fucking decade?!

Wrath surges, hot and blind and red, a fire that wakes the slumbering flame in his gut. He shoves Mukuro away, swings his legs off the bed, and stands. When his knees buckle, he stands again. Takes a step, another, on unsteady feet that carry him forward anyway.

Mukuro’s saying something, calling his name, but Xanxus doesn’t care. Doesn’t hear it.

“I’m gonna kill him,” Xanxus snarls. “I’m gonna kill that old man and burn the whole fucking Vongola to the ground. I’m gonna be Boss. I’m the one who deserves to be Boss. I—”

Surprisingly strong arms shove Xanxus back, and he crashes onto the bed. The symbol in Mukuro’s left eye shifts into a single horizontal stroke, and from absolutely nowhere, vines erupt into existence, like the ones that used to coil around the old church where they first met as kids. They snake around Xanxus’s wrists and ankles, pinning him to the mattress with vicious precision.

Flat on his back and fuming, Xanxus blames it on muscles that haven’t worked in years, because that’s the only way the shrimp could’ve trapped him like this, no matter how many damn inches he’s grown or how his illusions have gone from ridiculous little sprouts to full-fledged, solid tentacles.

“Get these things the fuck off me!”

The reply comes calm and maddeningly even. “I will, if you swear to calm down and stop trying to hurt yourself. You’re not healed. You need to move slowly.”

Xanxus yanks at the bindings, rage rising like bile. “The fuck—I already told you I don’t need your goddamn help! I’m gonna bash your skull in, you creep. I’m gonna destroy you, you hear me?!”

Before he can spit another word, Mukuro moves. In one fluid motion, he straddles Xanxus on the bed, arms braced on either side of his head. He leans in, and presses his mouth to Xanxus’s.

The attack is so unexpected that it doesn’t register for what it is right away. It’s not until Mukuro’s lips move against his that Xanxus realizes—

He’s being kissed.

As hypersensitive as Xanxus is to the heat right now, Mukuro’s lips feel like fire, burning away the resistance, the fury, melting the fight out of him before he can get a grip on it. Fingers slip into his hair, winding and tugging with the bold, possessive ease of hands that were always meant to be there.

By the time Mukuro pulls back enough to meet his eyes, the vines are already retreating. Xanxus would love to start yelling again, to throw a punch or two, only he’s suddenly too tired to fight. Disoriented, sluggish... exposed. All he wants is to lie there and surrender to the ridiculousness of his life.

“The Vongola, the Mafia... they never mattered.” Xanxus can’t see the mouth speaking, only the glint of mismatched eyes above him. “It was always us, wasn’t it? I wanted to tear down the whole rotten world, too. But every time I pictured it burning, I’d think: what’s the point if you’re not there with me at the end?”

The words are hard for Xanxus to make sense of. “You—you left. You left me.” He hates how clingy that sounds. What has he been reduced to this time? Some idiot brat with a sob story and abandonment issues, latching onto a kid who was barely even old enough to talk? If anything, it should’ve been the other way around.

The fingers in his hair move, threading in deeper, stroking gently.

“My captors caught me sneaking out,” Mukuro offers in reply. Xanxus wishes he could find the words to say Mukuro doesn’t owe him an explanation. Then again, if Mukuro really did spend years obsessing over someone he met a handful of times, that means he’s just as screwed in the head as Xanxus, and any effort to inject logic into their exchanges is pointless. “They put me in a higher-security cell at the lab. It took years to break out.”

Xanxus stares. He can feel Mukuro’s breath against his lips as he speaks.

Thinking is impossible, so Xanxus deliberately doesn’t, not when soft, warm lips find his again and clothed hips grind down against his bare skin, sending his long-frozen nerves into immediate overdrive. The once-gentle fingers in his hair tighten, pulling a gasp from Xanxus that grants a foreign tongue entry into his mouth. Xanxus slides his sore arms around Mukuro’s back, holding him in place, making sure he doesn’t vanish like he did last time.

“Oya,” Mukuro mutters, a little breathless against Xanxus’s ear. “As much as I’d love to keep going, your body’s in a very weakened state. You should rest... for now,” he adds, punctuating it with a playful nip to Xanxus’s lip.

Xanxus has half a mind to grab Mukuro by the throat and throw him down, show him exactly who’s in a “weakened state,” except every muscle in his body is loudly protesting the idea. So, grudgingly, he lets it go.

“Tch,” Xanxus scoffs. “Next time you start something like this, you’d better be ready to finish it, shrimp.”

The storm rolls on in the distance, thunder rumbling far away. Xanxus lies back against the pillow, eyes half-lidded, body aching in places he didn’t know he had.

Mukuro hasn’t moved far. He’d gone to fetch a towel, which he dropped over Xanxus’s crotch with a remark about “preserving his decency,” to which Xanxus had snarled a “fuck you,” and Mukuro, in turn, had replied with a smooth “I’ll look forward to it.” And that was when Xanxus ran out of replies.

To make things even stranger, Mukuro’s back in the chair beside the bed, tracing idle patterns across Xanxus’s wrist like they have all the time in the world.

Do they? Xanxus doesn’t know. Time feels different now that he’s apparently lost a shit-ton of it, like it’s moving sideways instead of forward. For Mukuro, who even as a creepy little kid was spouting crap about cycles of death and rebirth, this probably feels like any other Tuesday.

Xanxus is only now starting to catch up.

A thought surfaces about Squalo, the rest of the Varia, what might’ve happened to them, where they are now, if they’re even alive. Xanxus’s nowhere near the level of mental energy required to process any of that, though, so he settles for meeting Mukuro’s mismatched stare and says, “You know.” His voice comes out raspy, which annoys him. “You’re still a fucking weirdo.”

A small smile. “And you’re still terrible at saying thank you.”

Xanxus stares at the ceiling for a long beat before speaking again. “You remember that church?”

Mukuro hums. “Of course.”

“The first time I saw you, I thought you were a ghost.”

“Mm.” Mukuro’s wicked lips curve into a lazy smile. “You might not have been wrong... Maybe you needed a friend, and so you invented one, out of nothing. It’s possible, isn’t it?”

Lightning flares again beyond the curtains, and Xanxus almost sees it: the stained glass, the rain-warped wood, the dust over broken pews.

“Storm’s just like back then,” Xanxus murmurs into the air, a non sequitur after the other man’s last remark. He exhales and lets his eyes slip shut, giving in to the pull of drowsiness. He feels safe, which, in itself, might be nothing more than another of Mukuro’s illusions.

For once, Xanxus’s okay with being fooled.

Fingers curl loosely around his. “This time,” the voice beside Xanxus whispers, “I’m not disappearing with the lightning.”

 

~ The End ~ 

Notes:

Hi there, thank you so much for reading 🫶

If you'd like, feel free to leave a kudo to feed my little writing brain, and comments are also very welcome! I truly cherish every single one, and they always make my day 🥹

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