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Senku had always approached attraction the same way he approached everything else: data.
There was an objective part to it. Observable phenomena that could be replicated. Hormonal responses. But beyond that the whole thing lost the plot, wrapping evolutionary incentives in social theatrics that had nothing to do with the biological foundation of the matter.
People saw someone ‘hot’ and promptly lost fifty IQ points.
He’d spent years watching Taiju stare at Yuzuriha like a man witnessing divine revelation and thinking, You are biologically compromised.
Worse, even — sometimes people saw someone that the current conventions declared as hot and brainwashed themselves into feeling attracted.
It was embarrassing for the species, honestly.
A face was a face.
Symmetry activated certain reward pathways, sure. Certain proportions statistically correlated with what humans interpreted as attractive. That was just neuroscience. An evolutionary response to features that signaled ‘this person is healthy and has good genes’. Nothing worth short-circuiting over.
And then Asagiri Gen walked into his life with that stupid voice, impossibly soft skin and slanted eyes surrounded by thick eyelashes, and suddenly Senku understood why civilizations collapsed.
Not theoretically. Empirically.
Which was deeply annoying.
The first problem was Gen’s face.
Scientifically speaking, it made no sense. No human being should have features that coordinated that well together. The eyes were too sharp, the mouth too expressive, the bone structure unfairly balanced between elegant and punchably smug.
And the hair.
Senku had seen Gen on TV and magazine covers in the modern era, always in passing before he rolled his eyes and clicked his tongue, a dismissive comment locked and loaded in the tip of his tongue waiting for the second anyone praised the shady mentalist.
Byakuya had loved Gen’s shows. His father had been a man of science through and through, but he’d never lost his child-like fascination for life. That included magic tricks and illusionism. Where Senku’s brain immediately tried to pick apart each diversion strategy, hidden mechanism and sleight of hand, Byakuya absorbed them with stars in his eyes. At some point, Senku had given up in criticizing the show, an unspoken fondness bubbling low in his chest at his father’s amusement.
It still hadn’t warmed him up to the whole mentalism stuff, much less drawn his attention to Gen's looks like it happened to a non-negligible part of the audience. Senku had found him pretty generic, really. Slender build, spotless pale skin, shiny black hair — the standard. Pleasant enough to appear before the masses, not that attractive that he was known for it.
Post-petrification had revealed the white under the hair dye and, oh, that had garnered Senku’s attention.
The two-toned hair with the ridiculous asymmetrical cut should have looked absurd. Instead, it somehow made him more attractive, softening and complimenting the angles of his face in ways that violated several natural laws. And probably a couple warfare regulations as well.
The second problem was movement.
Gen moved like he was aware people were looking at him. Not in an arrogant way, exactly, more like he’d spent his entire life understanding attention as a physical thing he could hold in his hands and bend at will.
Every gesture deliberate, smiles calibrated to the exact degree, glances that pierced every defence.
It was manipulative.
To his chagrin, Senku found himself respecting it immensely.
The third — and by far worst — problem was that Gen was smart.
Not laboratory smart. Not equations-on-a-wall kind of smart. But terrifyingly people-smart. He read rooms the way Senku read chemical formulas. A natural gift, perhaps, but it was clear that Gen had harnessed it and honed it into his ultimate tool and weapon.
And, once Senku realized that, he realized something significantly more dangerous: Gen knew exactly what he was doing to him.
Which meant he’d lost the game before he even knew there was one.
“You’re doing it again,” Gen said lightly one day.
Senku looked back up from the lightbulb he’d been in the process of assembling. “Doing what?”
“That thing where you sneak glances at me like you’re trying to reverse-engineer my skeleton.”
“I already know how skeletons work.”
“Mhm.”
Gen leaned against the doorway of the lab, early afternoon light catching the pale side of his hair, tinting it faintly in gold. His posture was relaxed, eyes half-lidded. Entirely too pretty for post-apocalyptic conditions.
Senku forced himself to continue coiling wire.
“You’re imagining things.”
“Senku-chan,” Gen said, amused, the lilt of his voice doing weird things to his pulse, “you are aware I can find out where Chrome-chan has been mining just by looking at the mud on his soles.”
“Your point?” he grumbled, trying to sound bored.
If the quirk on Gen’s lips was anything to go by, it didn’t work.
“I may not have Kohaku-chan’s superhuman sight, but you should know by now that I’m rather perceptive.”
“That’s different.”
“You have been observing me closely.”
Senku clicked his tongue, while stubbornly ignoring the heat that started to crawl up his neck.
He would have loved to wave it off as irritation.
“Keep telling yourself that,” he grumbled.
Gen’s smile widened by a fraction. The effect was immediate and catastrophic. Senku became abruptly aware of several things simultaneously:
One: Gen smelled faintly like smoke from the furnace, the herbs he liked to collect and soap.
Two: the way his clothes hung off his frame was somehow more flattering than the pretentious suits he wore in the modern era.
Three: this information was completely useless and his brain needed to stop storing it immediately. And it especially needed to stop imagining what it would feel like to wrap his arms around Gen’s slender waist and let his scent envelop him.
“You know…” Gen mused, “for someone who claims human attraction is irrational, you’ve been acting awfully weird lately.”
“I’m not weird.”
Gen rose his brows slightly, looking very much tempted to challenge that statement. Instead, he did something arguably worse.
“You stared at my mouth for eight full seconds yesterday,” he said.
Senku nearly dropped the filament, his heart jumping to his throat.
“You ten billion percent made up that number.”
“Oh? So you admit you were staring.”
‘I walked straight into that one.’
His mind scrambled for something to say while cursing all the damned mentalists to ever exist, and Gen in particular. “…Shut up.”
Okay, perhaps not his brightest moment.
Gen laughed softly, clearly delighted.
And that was another one in the growing list of issues. His laugh.
Senku had not previously understood how sound could alter a person’s nervous system. Now he did. A truly horrifying discovery.
“Aw,” Gen said, tilting his head, “Senku-chan’s flustered.”
“It's called annoyance, mentalist.”
“The two aren’t necessarily mutually exclusive.”
Senku finally looked at him directly, which proved a mistake. Because Gen was already watching him. Not teasingly, not this time, just… observing, his grey eyes dancing around Senku’s face with a focus that was almost gentle. Warm. Intent. Curious.
And there it was again — that strange, destabilizing sensation Senku had spent months attempting to categorize and failing every single time.
His pulse ticked up.
Gen’s expression softened almost imperceptibly.
“There it is,” he said quietly.
Senku frowned. “What?”
“That look.”
“What look?”
“The one where you realize you like me.”
Silence.
Senku opened his mouth automatically, prepared with at least six rebuttals and three psychological deflections.
They all faded before the words made it to his lips.
Because the deeply unfortunate truth was that Gen was correct. Not only correct. Smugly, devastatingly correct.
The worst — or best? — part? Beyond the satisfied smirk, a different feeling flickered in Gen’s expression. Something soft and genuine, tentative, too tender to show directly yet. Something that dangerously resembled hope.
For a second, the floor disappeared from under his feet.
Ishigami Senku, who had once considered romantic attraction a catastrophic lapse in human judgment, had somehow developed a severe case of wanting to stare at Asagiri Gen indefinitely.
The universe, clearly, was a comedian.
But maybe, just maybe, it wasn’t the worst thing in the world.