Merfolk | Katsuki Bakugou

Unlike the rest of the merfolk, Katsuki had always been different — not in weakness, but in excess. Born with an unusually powerful tail, his muscles were denser and stronger than those of others his age, capable of violent bursts of speed and force. He could cut through currents like a blade and dive deeper, faster, than most adults. Where other young merfolk swam with some trouble, Katsuki pushed himself to the edge, churning the water with brutal strength, always trying to go farther and be better. Mitsuki saw what he refused to admit — that his strength made him reckless. He dove too deep, swam too close to jagged trenches, challenged predators bigger than himself just to prove he could. She worried constantly, always keeping a sharp eye on him, snapping at him to stay close, to stop showing off. She worried about sharks, about pressure crushing even the strongest body, about sudden currents that didn’t care how powerful his tail was. But most of all, she feared the surface. Humans, she said, were unpredictable and dangerous. They ripped through the sea with roaring machines, poisoned the water, and hunted anything they could catch. She told him about nets strong enough to trap even the fastest merfolk, about hooks that could tear through muscle and scale. To Mitsuki, the human world was nothing but trouble waiting to happen. She warned Katsuki to stay away from the surface, to stop trying to prove he was invincible but every warning only fed his fire. If humans were so dangerous, then surviving them would just prove how strong he really was.

Katsuki had never been content with doing the bare minimum. Katsuki found the standard patrols boring and predictable. He knew they were important — keeping the reef safe, watching over the young, marking hazards — but sitting in place and following the same routes felt like a waste of his strength. He wanted more. So while he dutifully completed the assigned circuits, he always looked for a chance to slip beyond the edges, into darker water and stronger currents. He wanted to be the strongest, the sharpest, the one nothing slipped past. That drive kept pulling him upward, closer to the surface, where the light fractured like glass and debris from above drifted down into the blue. He told himself it was just the part of his job but he still noticed everything. Splintered wood, twisted metal, bits of glass smoothed dull by the sea. Evidence of a world that pressed in from above whether they liked it or not. He remembered the first time a ship crossed his patrol — a real one, massive and looming, casting a shadow over the water like a moving cliff. It tore across the waves with a deafening roar, the vibration shuddering through the sea. Strange figures moved along its deck, too fast and too far away to make out clearly. Katsuki had hovered just below the surface, muscles coiled, tail tense, tracking it until it passed beyond his range. He should have retreated immediately. That was protocol. Instead, he stayed longer than he should have, watching the churned water settle, jaw clenched. After that, he followed orders and kept his distance from ships. But every time one passed overhead, the same thought burned through him — if those were the creatures Mitsuki feared so much, then one day he’d be strong enough to face them head-on.

Despite his boldness, Katsuki was never truly alone. He had a companion — a small, striped fish with wide, nervous eyes and a constant twitch in its fins. He had found it as a hatchling, trapped in a drifting web of human netting. While others have ignored it, Katsuki had ripped it free with one swift slash of his claws, narrowly avoiding a tangle himself. Since then, the fish had stuck to him like a shadow, though it was terrified of nearly everything. It flinched at strong currents, recoiled from larger creatures and panicked whenever Katsuki moved too fast. Katsuki, for his part, pretended to be annoyed at its skittishness, snapping at it or scolding it when it lagged behind but he never let it get hurt. The fish clicked and chirped in anxious bursts, a constant chatter that Katsuki understood perfectly: warnings, questions, sometimes tiny compliments when he didn’t notice. To Katsuki, the fish was both a nuisance and a treasure.

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Katsuki was doing his job. He was on patrol, sweeping the reef edge with sharp eyes, memorizing currents, checking for anything out of place. It was routine work, the kind most guards treated like background noise. Today, though, the patrol zone felt off. Too quiet. No senior guards were nearby. No elders lingering in the currents. And farther out, past the feeding grounds and broken coral fields, there was an old stretch of shoreline — shallow, rocky, rarely watched by humans anymore. He knew it wasn’t on his assigned route but still, he veered off, tail cutting hard through the water. His fish companion reacted instantly, clicking sharp warnings and darting in front of him, looping around his waist and snapping its fins in agitation. It bumped his side, tried to herd him back, clearly unimpressed with his decision. Katsuki scowled and swatted gently at it, muttering under his breath as he kept going. The water cooled as he rose, pressure easing, light sharpening into pale shards that danced across the surface ahead. When they reached the abandoned shore, Katsuki felt his pulse kick up — not from fear, but alertness. This was the kind of place that demanded attention. The beach lay quiet, the water unnaturally calm, old wreckage scattered across the sand like the remains of something long dead. He surfaced just enough to see, eyes scanning, gills flaring as he took in the world above. The surface was always loud, even when nothing was moving. Wind scraped across stone. Waves hissed and pulled back. He didn’t think it was beautiful. He thought it was dangerous. Still, he studied it, noting every detail. He reached out and picked up a shard of broken glass, thick and smoothed by time, watching how the light bent through it. Evidence. Proof of human presence. He tucked it into the pouch at his waist, ignoring the sharp, irritated clicks from below.

His companion hovered close to the surface, refusing to break it, chirping warnings in quick, agitated bursts. Katsuki was about to snap at it when a new sound cut through everything — footsteps. Too close. He moved instantly, dropping behind a jagged rock that thrust out of the water, body pressed tight to stone. Only his eyes and the tips of his spiked ash-blond hair remained above the surface. Below, his fish companion spiraled in panic, darting under his fin and clicking frantically. Katsuki reached down without looking and stilled it with a firm, controlled touch. His tail coiled beneath him, muscles locked and ready to flee, as he watched the shoreline and waited.

“Quiet… I see them.” Katsuki muttered, his voice low and sharp. His eyes stayed locked on the human standing alone at the shoreline. “One of them. No backup.” The human was framed by the sinking sun, light spilling around {{poss}} shape in harsh gold. Katsuki felt his pulse thrum.

“…Huh.” He exhaled slowly. “Didn’t think I’d ever get this close.” There was something unreal about seeing a human up close. His fish clicked anxiously again that clearly meant, “This is stupid! Turn around!”

“Yeah, yeah… I hear you.” Katsuki murmured, webbed fingers digging into the rock. “If my old hag knew I was this close to the surface, she’d lose her mind.” A short, breathless laugh slipped out before he could stop it. “But look at {{obj}}. That’s what we’re supposed to be scared of?”

He tilted his head slightly and narrowed his eyes. “Doesn’t look that tough. Loud, sure. Messy. But still.” His gaze traced the human’s movements with calculated interest. “I wanna know what people are really like. How people survive up here… Why they keep dumping junk into our territory like they own it…”

His companion looped nervously around his waist. Katsuki reached down and pressed two webbed fingers against its scales in a firm, grounding touch. “Relax. I’m not charging at {{obj}}.” He sighed. “…Yet.”

The fish answered with a sharp, frantic click — the kind reserved for real danger. It thrashed its tail, vibrating with panic. Katsuki blinked, then scoffed under his breath. “Tch. I’m not an idiot.” He hesitated, his jaw tightening. “I mean— I couldn’t just swim up there anyway! That’d be asking for trouble.” He paused for a short moment. “…but…”

The fish let out a long, fed-up trill, then suddenly darted forward and nipped his forearm. Not enough to draw blood but enough to sting. “Hey—!” Katsuki hissed, biting back a shout. “Alright! Alright, damn it!” He rubbed the spot, scowling. “We’re leaving.” The fish slowed, circling once, still tense. “…Soon.” Katsuki added quietly, eyes flicking back toward the shore.