In Theory [Senku x Reader]

The stars are not afraid to appear like fireflies." — Rabindranath Tagore

The stars were bright—brighter than they ever were in the heart of Tokyo. Out here, they stretched endlessly across the sky, untouched by neon or smoke, the kind of sky you could only see in a world stripped bare.

The wind whispered through the tall grass, gentle but insistent. It carried the scent of smoke and earth, mingling with the rustle of leaves and the far-off chirp of crickets. From a distance, three figures stood silhouetted against a lantern's soft, flickering halo. Its light wavered with the breeze, casting elongated shadows across the hillside.

Somewhere behind, a voice called—faint, familiar, almost lost to the wind.

You turned, instinctively.

A memory, maybe. Or the shape of one, barely formed.

Tick.

The fire crackled in the silence that followed, its core glowing a restless orange-red. It devoured everything offered—twigs, brittle bark, splinters of old wood—consuming with a hunger that bordered on desperation. Each new piece ignited with a soft hiss, sending a scatter of embers spiraling skyward like sparks of thought slipping away before they could be spoken.

The flames breathed in and out, like lungs that had forgotten how to rest.

Above, the smoke trail thickened and spiraled higher into the sky—no longer an accidental column, but a deliberate one. Dark, structured.

Two figures lingered by the glow, the silence between them too intentional to be idle. Waiting. Expecting.

There was an odd kind of stillness to it all—calm, but not peaceful. A stillness you only find in the breath before something falls.

You're crouched low beside the fire pit, elbows resting on your knees, your gaze fixed on the dying shimmer where the last of the black powder hissed faintly—white sparks blooming briefly before fading into ash.

The air was sharp with the scent of potassium nitrate, charcoal, and sulfur. A chemical tang that stung the back of your throat, oddly comforting. Familiar.

Tick.

You snorted—quietly, involuntarily.

Senku, crouched nearby with a reed between his fingers, glanced over. One brow arched in that trademark mix of suspicion and mild curiosity. "What?"

"Nothing," you replied, still half-grinning. "I just remembered the time you randomly joined that dodgeball tournament when we were kids. Shocked the hell out of all of us. Even Byakuya had to double-check if he'd heard you right."

Senku gave a soft, unamused grunt. "Strategic dodgeball is practically applied physics. Of course, I joined."

You laughed under your breath, picking up the pouch that had been used to carry nitrate, now blackened at the seams. You ran a finger along the soot-smudged rim, thoughtful. "Sure. But Byakuya was less concerned about your math and more about the fact that you brought a homemade explosive as a 'theoretical advantage.' You almost got banned from the entire Tokyo municipal sports system."

Senku's eyes gleamed with a knowing glint. "You say that like the two events weren't connected."

Tick.

"Besides, we won, so who cares?"

You snorted again, shaking your head.

The conversation felt... off. Too easy. Too convenient. Like the words were there to plug a silence neither of you wanted to confront. As if talking was just a vessel. A stalling mechanism.