In Theory [Senku x Reader]

0.4 | Call It As It Is

You heaved an exaggerated sigh, swinging your legs from your perch. "Gee, thanks for the confidence."

Taiju barely heard you, his wide eyes still locked onto the impossible sight before him—frozen somewhere between disbelief and overwhelming relief. His mind struggled to reconcile the image.

You were alive.

You smiled, effortless in your movements as you flipped yourself upright onto the branch, balancing with a fluid ease that came only from months of practice, almost like you've done it a thousand times before.

And then—

"Hah."

A chuckle.

Not yours.

No, you were still in front of him, the barest hint of amusement lingering in your expression as you swung lazily back and forth on the branch.

This laugh was different—lower, sharper. Threaded with dry amusement. And it shot straight through Taiju's system, sparking a visceral, bone-deep recognition.

Because there was only one person in the entire world who laughed like that.

A second figure stepped out from the shadows behind you, half-obscured by the leaves—feet planted firmly on the branch, as if gravity were a mere afterthought.

White hair, streaked with green at the tips. Two familiar strands framing his face. A makeshift tunic of tanned hide slung over his lean frame, the fabric worn but practical.

And plastered across his sharp features—because of course it was—

That smirk.

Senku.

"Well, look who's finally awake." His voice cut through the space between them, casual, self-assured—like the three of you hadn't been separated by thousands of years. Like this wasn't the first time in millennia that Taiju had heard another human voice. Like this was just another ordinary day after school.

"Yo." His crimson eyes gleamed in the speckled sunlight, glinting with something unreadable. A private amusement, a knowing edge. "Good morning, you big oaf."

One hand held a bundle of long, stripped logs, the other gripping what could only be described as a primitive, handmade axe—fashioned from stone and wood, worn smooth from use.

Taiju gawked. His brain outright stalled.

Not just at Senku, but at both of you.

Alive. Whole.

Not frozen in stone. Not lifeless statues.

But real. Breathing. Here, standing before him, clothed not in the uniforms he last remembered, but in something rougher—rugged, handmade, built for survival. Even your skin bore the marks of time spent in the elements—sun-kissed, hardened by exposure.

But none of that mattered.

Because right here, right in front of him, the two of you were okay.

After endless hours surrounded by nothing but statues upon statues—frozen faces locked in expressions of fear, defiance, or quiet resignation—after a silence so suffocating it had nearly driven him mad, after relying on nothing but the rustling of trees as his only company—

You were both here.

Here with him.

Just like that summer's day on the beach, the salt-heavy breeze tangling in your hair as the three of you argued over the plausibility of Senku's latest experiment. Just like those exhausted afternoons in the old classroom, where the ticking of the clock and the scratch of pencils filled the silence as Senku scribbled complex formulas, you tried to finish them first, and Taiju doodled aimlessly in the margins of his notebook. Just like all those late nights spent at Senku's house—his place cluttered with half-built contraptions and scattered science journals—where you sat cross-legged on the floor, Senku's voice a constant stream of explanations, and Taiju's laughter filled the space between.