Chapter Text
The air had taken on that sharp, silvery edge that came just before winter - the kind that stung the lungs on a deep breath and made every exhale shimmer briefly in the cold. The sound of the river had slowed, thickened, its surface catching light like liquid glass as if it too were bracing for the freeze to come.
The Kingdom of Science pulsed with the rhythm of preparation. Axes thudded in steady cadence as firewood piles grew higher each day. Hammers rang against iron, ropes creaked, and the scent of resin and smoke hung heavy in the air. Tarps stretched taut over grain stores, barrels were sealed with wax, and the faint crackle of drying herbs wafted from the infirmary sheds.
At the heart of all this motion was Rui.
Her coat sleeves were rolled past her elbows, revealing wrists ink-smudged with graphite. Strands of hair escaped her loose tie, brushing the back of her neck as she bent over a table cluttered with notes, ledgers, and half-finished calculations. The tip of her pen darted across paper in brisk, confident strokes - no hesitation, no wasted movement.
The lab had transformed into her war room. Charts and inventories hung from the walls in neat, overlapping layers - lists of dried provisions, medicinal stock, lamp oil, and winter blankets, each line marked with Rui’s tidy handwriting. Ink pots glimmered faintly in the weak sunlight cutting through the paper windows. Around her table, a few of the younger villagers hovered, half in awe and half anxious, awaiting orders.
“Group three, you’re handling insulation,” Rui said, her tone even but firm. She pointed to a column in the ledger without looking up. “Use the straw-mud mixture Kaseki-san tested yesterday. Keep the ratio consistent - if the mud layer’s too thin, the walls will crack once it freezes.”
“Yes, ma’am!” the group chorused, already hurrying out.
“And Chrome,” she added, still writing as she spoke, “reinforce the roof beams this time. You skipped them last year.”
Chrome froze mid-turn. “Wait - you remember that?”
Rui’s only response was a small, knowing tilt of her head - a smile tugging faintly at the corner of her lips.
Senku leaned lazily against the doorframe, the cold light outlining the sharp edges of his hair. For once, he wasn’t buried in chemical formulas or machine blueprints. His usual focus - the kind that consumed him completely - seemed to falter, redirected to the quiet order before him.
He should have been in the workshop by now, calculating thermal resistances for the new prototype or refining ethanol fuel batches. Usually, he’d already be two steps ahead of everyone else - but since reviving Rui, the Kingdom had changed. The bottlenecks that once tripped him - logistics, planning, coordination - were now handled before he even noticed them forming. Rui worked like an unseen algorithm smoothing the inefficiencies of their world, aligning chaos into a pattern.
She didn’t demand attention the way some leaders did. Her strength was quieter, woven through tone and timing - a precise, human metronome. Every instruction was measured, every correction gentle but unyielding. She moved through the organized storm like a conductor who never needed to raise her voice, and somehow the noise became harmony.
Senku’s gaze followed her without meaning to - the quick turn of her wrist, the steady poise in her shoulders, the faint concentration lines softening her brow. She looked perfectly at home in the storm she had built.
He realized, with a faint twitch of irritation at himself, that he’d been staring again.
Francois passed behind him, the soft rustle of their uniform brushing against the wooden doorway, a basket of rolled parchment balanced effortlessly in their arms. “Apologies, Master Senku,” they said smoothly, their voice carrying the precise cadence of someone who never once stumbled over words. “I didn’t mean to interrupt your daily admiring, but this basket needs to come through.”
Senku stepped aside without thinking. “Observation,” he corrected automatically, crossing his arms.
“Of course.” Francois’ lips curved in that subtle, elegant way that always made their statements sound harmless - until you thought about them twice. “A rather intensive observation, if I may note.”
Senku’s brow twitched. “You’re reading into things that don’t exist.”
“Am I?”
He didn’t dignify that with an answer.
Rui was crouched now beside a crate, comparing two columns of figures. The pale winter light slanted through the window, catching in her hair as it slipped loose over her shoulder. When she leaned forward, her fur collar brushed her cheek, and she absentmindedly pushed it aside with the back of her wrist - a small, unremarkable motion that nevertheless caught him completely off guard.
Get a grip, idiot, he told himself. It's just biochemical attraction. Puberty speaking. Serotonin, dopamine. Nothing revolutionary.
But as he watched her smile - soft, fleeting, genuine - something unquantifiable tightened in his chest. The warmth spreading through him didn’t feel like a chemical reaction. It felt like something messier, something entirely unscientific.
It felt human.
“Ishigami-kun?”
Her voice snapped him out of it. Rui had turned, clipboard in hand, her expression expectant but gentle. “Can you double-check the insulation data before nightfall? I want to be sure the cold storage can hold a stable temperature.”
He blinked, delayed by a full beat. “Right. Yeah. Got it.”
Her lips curved - that quiet, devastating smile that seemed to bypass reason entirely - and she turned back to her notes, already lost again in the rhythm of her work.
Senku exhaled slowly, rubbing the back of his neck as though he could physically scrub the warmth off his skin.
Francois reappeared a moment later, as soundless as a shadow, voice pitched just low enough to pass for discretion. “You appear to be thawing before winter even begins, Master Senku. Shall I prepare a washbasin?”
Senku shot them a flat, withering look - one that should have ended the conversation - but the corner of his mouth betrayed him, tugging upward despite his best effort to stop it.
Yeah. But he finally admitted to himself - wordlessly, and with no equations left to hide behind. I'm in trouble.