In Theory [Senku x Reader]

0.5 | The Familiarity of Snow

You snicker, settling onto the unoccupied log beside the flames, pulling your makeshift fur coat tighter around yourself. The fire crackles low, a fragile but crucial barrier against the brutal winter that gnaws at your exposed skin.

It was December now. You were sure of that.

Time had passed steadily—Senku had kept track, as he always did, and from there, it hadn't been difficult to count for yourself. Back in the old world, December meant the glow of city lights, steaming cups of convenience store coffee, and students dragging their exhausted bodies toward winter break. It meant curling up inside, not braving the elements like some prehistoric nomad.

And if your calculations were right, then today was—

You hesitate.

You glance at him, lips parted, the words forming at the back of your throat. But then you really look at him—at the sharp lines of his face, the permanent furrow of his brow, the exhaustion he never fully shakes. His shoulders are tight, his fingers deft but rigid as they rest. The weight of rebuilding civilization—of carrying all of it—rests so heavily on him that for a moment, you think you can see it.

The words change at the last second.

"Wanna bet it's going to explode again?"

Senku exhales sharply through his nose. "Don't jinx it with your garbage luck."

You give him a flat look. "You're one to talk."

He finally spares you a glance, one brow arching, smug amusement flickering behind crimson eyes. "Oh yeah? Care to explain the time you nearly set yourself on fire trying to cook dinner last month?"

"That was one time," you shoot back, pointing at him. "Meanwhile, you've practically got a loyalty card with spontaneous combustion."

"Please," Senku scoffs. "I've never once spontaneously combusted."

You scoff, the words from before retreating, burying themselves back down. They don't belong in a time like this, in a world like this. "Are you saying you forgot when you—" you gesture vaguely toward the shed behind you, "—detonated an entire batch of failed nitric acid and nearly knocked yourself unconscious with the fumes?"

Senku clicks his tongue, unimpressed. "Tch. That was controlled."

"Oh, was it? Controlled?" You cross your arms. "You screamed like a dying cat."

"I warned you it was going to explode," he argues, jabbing a finger at you.

"Oh, right, my mistake," you reply dryly, brushing snow off your coat. "Next time you shout 'Oh shit, oh shit, oh shit!' I'll be sure to recognize it as a calculated and controlled experiment."

Senku huffs, muttering something under his breath that sounds suspiciously like "still better than burning dinner..."

"You're just mad I make better food than you."

"Yeah," he deadpans, leaning back onto his log. "Because the bar's so high when half your recipes are just 'heat until slightly less inedible.'"

"Better than toxic waste."

He opens his mouth—probably to argue some half-baked justification—but pauses instead. For a moment, the cold presses in, biting and sharp.

You're both quiet.

A draw.

Your gaze shifts to the snow-packed walls encircling the fire—a necessity, given the relentless wind. The three of you (though mostly Taiju) had spent the better part of the week fortifying them, ensuring the flames wouldn't be snuffed out by an errant gust. The packed ice glows faintly in the firelight, a temporary bastion against the ever-hungry cold.