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It started with a rock. A really shiny, really cool rock. You’d found it in the schoolyard during recess, glinting under the sun like a tiny captured star, and naturally, there was only one person who could properly appreciate such a treasure.
“Senku! Look what I found!” You ran up to him, shoving the rock into his hands like it was the most important thing in the world.
Senku barely looked up from his book before adjusting his grip on the stone, inspecting it with sharp, calculating eyes. “Hoh? Not bad. This is a piece of pyrite—fool’s gold.”
You gasped. “Gold?!”
“Fool’s gold,” he corrected, rolling his eyes. “It’s an iron sulfide mineral. It looks valuable, but it’s actually worthless.” He pointed over to the boxes the theater kids brought, “It probably just fell out of that.”
You blinked, then grinned. “So, it’s like the fake treasure in pirate movies?” Of course you didn’t listen.
“Exactly.” Senku smirked, obviously pleased you were keeping up with the scientific side of his observations. “It’s formed in hydrothermal veins when iron and sulfur combine under heat and pressure. You probably found it because of the mineral composition in the area—”
Before he could go off on a full-blown science lecture, you leaned forward and—
Licked.
His cheek.
Senku froze.
It gave you enough time to lick the rock. He didn’t even want to think about where it had been.
For a full three seconds, he was just a statue, his brain absolutely refusing to process what had just happened. His eye twitched. “…THE HELL WAS THAT?!”
“I licked you, so you’re mine now!” you declared proudly, hands on your hips. That’s how it worked, right? That’s what your older cousin told you about her puppy. She said dogs licked things to claim them. And Senku was your best friend, so naturally, licking him made it official!
Senku reeled back like you’d electrocuted him. “That is NOT how science OR ownership works, you primitive ape!!”
“Too late, I called it!” You crossed your arms, smirking. “Ishigami Senku is officially mine. No take-backs.”
He wiped his cheek aggressively, looking more scandalized than you’d ever seen him. “First of all, that’s completely unscientific. Second, that’s disgusting! Third—” He scrubbed his cheek harder. “WHY WOULD YOU LICK ME?!”
You giggled. “Because you’re mine, duh.”
Senku’s face burned bright red, and for the first time ever, he had no comeback. He just grumbled something under his breath, turned on his heel, and stomped away—probably to disinfect his face a hundred times.
You picked up your shiny rock and grinned.
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It had been three hours since ‘The Incident.’
Senku had spent the remainder of recess scrubbing his cheek with the intensity of someone trying to remove radioactive contamination. He had also, to your mild amusement, been uncharacteristically quiet since then. No rambling about physics, no smug comments about how he was the smartest person on the playground. Just red ears, wide eyes, and the occasional distant stare into the void.
Not that you noticed.
The school bell rang, and as always, you waited outside the gate for Senku so you could walk home together. He was taking a suspiciously long time to emerge, and when he finally did, he kept two feet of distance between you, eyes darting anywhere but in your direction.
You tilted your head. “Hey, you okay? You’ve been weird all day.”
“I’m fine,” he said stiffly.
You blinked. Shrugged. And then—as always—grabbed his wrist and started dragging him home.
This was routine. Senku, being Senku, would get so lost in his thoughts that he’d walk directly into traffic if left unsupervised, so it had become your personal responsibility to make sure he actually got home in one piece. Usually, he just let you do it. Today, however—
The moment your fingers curled around his wrist, Senku jolted like you’d electrocuted him.
“W-WHAT NOW?!”
You glanced back at him, confused. “…What?”
“Y-You’re—” He clamped his mouth shut, face burning even redder. You’d never seen him so visibly malfunctioning.
You raised an eyebrow. “Senku, you’re always lost in your head when we walk home. Do you wanna end up in a ditch?”
That seemed to shake him out of it, because he scowled and grumbled, “Tch, fine, whatever,” before reluctantly letting you drag him along.
Again—not that you noticed his existential crisis.
By the time you reached Senku’s house, his entire mood had not recovered. His dad, Byakuya, was already home, leaning against the doorframe with a knowing smirk.
“Well, well,” Byakuya said, arms crossed. “You’re later than usual. Let me guess—Senku got caught up in another experiment?”
“Nope!” you chirped. “Senku’s just being weird.”
Byakuya blinked. “Oh?”
Senku visibly tensed. “I’m not being weird.”
You squinted at him. “You spent the whole walk home redder than a tomato.”
Byakuya’s eyes lit up. Oh, he was already having too much fun. “Wait a second… Did something happen today?”
Senku froze.
You, however, nodded enthusiastically. “Yup! I licked him.”
The pregnant silence that followed could have had her baby before one of you spoke.
Byakuya blinked very slowly. “You… licked him?”
Senku looked like he was praying for a spontaneous meteor impact.
“Yup!” You grinned. “Because I licked him, he’s mine now.”
Byakuya immediately lost it. His booming laughter echoed through the street while Senku visibly died inside.
“PFFT—AHAHAHAHAHAHA!” Byakuya wheezed, clutching his stomach. “Oh man, I knew someone would get you one day, but this is beyond my expectations!”
Senku buried his face in his hands. “Kill me.”
“Nope, no can do, my boy,” Byakuya grinned, wiping a tear from his eye. “You’ve already been claimed.”
Senku made a noise like a dying cat.
Meanwhile, you just smiled, completely oblivious to your best friend’s utter suffering.
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Senku was not flustered.
Flustered was an illogical state of mind. It served no scientific purpose. There was absolutely no reason why his brain kept replaying ‘The Incident’ over and over again like a glitched-out record player.
Unfortunately for him, Byakuya wasn’t letting it go.
The entire evening had been filled with teasing. Every time Senku walked into the room, Byakuya wiggled his eyebrows at him. When they sat down for dinner, Byakuya stuck his tongue out just to watch Senku choke on his rice.
It was absolute hell.
But eventually, time passed. Senku convinced himself that it was a one-time thing. A weird, impulsive moment that you’d already forgotten about.
…Until the next day.
It was recess again, and you were crouched on the pavement, examining another rock. Senku sat nearby, scribbling formulas in a notebook. Things had finally returned to normal.
And then—
“Hold still,” you said.
Before Senku could process those words, you leaned over and—
LICK.
Except this time, you weren’t licking him.
You were licking Taiju.
Senku’s entire body short-circuited.
“W-WHAT?!” Taiju yelped, nearly falling over.
“There,” you declared proudly. “You’re mine now.”
Taiju jumped back up. “FOR REAL?!” You were unphased by his demeanor, courtesy of knowing the guy since diapers. “I HAVE TO LICK YOU BACK TOO!”
Senku stared. His brain refused to compute.
He knew it was stupid, unscientific, completely irrational—but for some reason, something in his chest clenched.
He scowled. “What the hell do you think you’re doing?”
You turned to him, tilting your head. Taiju’s mouth was obnoxiously close to your own pretty cheek. “What?”
“You—you already did that to me.” His voice came out more accusing than intended.
You blinked. “Yeah, but Taiju’s my friend too.” Said boy had some drool fall to the ground from how big his mouth was, still propped open in mid air. The big oaf.
Despite the warmth he normally felt for your antics today it was dulled. Senku felt something ugly twist in his stomach.
“Yeah, but you licked me first,” he muttered under his breath.
“What?”
“Nothing,” he snapped, crossing his arms.
Taiju, meanwhile, was still reeling. At least he had the decency to close his mouth.“Wait, so, uh… does this mean I belong to you now?”
You nodded firmly.
Senku’s eye twitched.
“No,” he blurted.
You and Taiju blinked at him. “No?”
“No.” Senku scowled, pointing at Taiju like he was an incorrect math equation. “That’s not how this works. You can’t just—just collect people.”
“…Why not?”
“Because,” Senku snapped, voice sharper than usual. “I thought you picked me.”
The words escaped before he could stop them.
Silence.
Taiju blinked. You blinked. Senku, realizing what he had just admitted, suddenly wanted to crawl into a hole and die.
You tilted your head. “Oh. You wanted to be special?”
“N-No, that’s not—” He stopped. Because that’s exactly what he had meant.
You grinned. “Okay.”
Senku frowned. “Okay, what?”
You leaned in—too close—and licked his cheek again.
Senku froze.
“There,” you said smugly. “You get double licks, so you’re extra mine.”
Taiju burst out laughing.
Senku made a noise like a dying computer. “I—that’s—” He stood up so fast he nearly knocked over his notebook. “THAT’S NOT—WHATEVER! I’M GOING HOME.”
And then, he fled.
Taiju wiped a tear from his eye. “Man, you really broke him, huh?”
You just grinned.
Best discovery ever.