Chapter 2: Thermal Shock
The climb had been a brutal, silent affair. Vines snagged at their clothes, thorns bit into their palms, and the humid air clung to their lungs like wet cloth. Katsuki led with a relentless, ground-eating pace, his focus absolute. Nala followed, her muscles screaming in protest, the empty cold in her veins a constant, gnawing companion. Every slip of her foot, every labored breath felt like a confirmation of his assessment: liability.
When the sharp, acrid scent of sulfur first hit them, they both paused, nostrils flaring.
“What is that?” Nala asked, her voice raspy from thirst and exertion.
Katsuki didn’t answer, just changed direction, pushing through a thick curtain of broad, waxy leaves. The foliage gave way abruptly to a small, rocky clearing. Steam rose in lazy tendrils from several pools of water, each one a milky, turquoise blue, carved into the black volcanic rock. The air was warm and thick, humming with the distant, subterranean rumble of the island.
“Hot springs,” Katsuki stated, his sharp eyes scanning the perimeter for any immediate threat. “Volcanic activity. Should be safe.”
He didn’t wait for her opinion. He walked to the edge of the largest pool, kicked off his battered boots, and without a shred of self-consciousness, peeled his sweat-soaked, grime-caked shirt over his head. His pants followed. He stood there for a moment, a study in lean, corded muscle and faded scars, backlit by the steamy haze, before stepping into the water with a low, appreciative grunt.
Nala remained by the tree line, her arms crossed. “A little warning next time.”
“You seen a guy before, Kono. Get in. The minerals will help with the muscle fatigue.” He sank deeper until the water lapped at his chest, leaning his head back against the rock. His eyes were closed, but she knew he was still aware of everything. Always.
Her own body ached with a deep, pervasive soreness. The promise of hot water was a siren’s call. Turning her back to him, she shucked off her pants and tank top, leaving on her underwear and a thin, practical sports bra. The air felt cool on her damp skin before she quickly slipped into the pool on the opposite side.
The heat was immediate and profound. It seeped into her bones, loosening the tight knots in her shoulders and back. She sighed despite herself, sinking until the milky water covered her collarbones. For a few minutes, there was only the sound of bubbling water and the distant jungle.
Then she felt it.
A twinge. Not a spark, but a sensation, deep in her core. A flicker of warmth that was entirely her own, separate from the enveloping heat of the spring. It was faint, like a single nerve ending waking up after being asleep. Her breath hitched.
“What?” Katsuki’s voice cut through the steam. His eyes were open now, fixed on her.
“Nothing.”
“Don’t lie to me. Your breathing changed.” He was watching her with that unnerving, predatory focus again.
She closed her eyes, trying to ignore him, to focus inward. The mineral-rich water seemed to be conducting something, acting as a catalyst. The emptiness in her veins wasn’t so empty anymore. It was… stirring. A low thrum of energy began to build, not sputtering and dying, but gathering. The heat within her rose to meet the heat of the water, intertwining, amplifying.
A gasp escaped her as a wave of warmth, real and powerful, flooded her system. It was too much, too fast after so long without. Her hands clenched on the rocky ledge. Her back arched involuntarily.
Katsuki was moving. Water sloshed as he crossed the pool in a few swift strides. He didn’t ask. He just moved into her space, his body caging her against the rocky edge. The steam wrapped around them like a shroud.
“Let it out,” he commanded, his voice a low growl near her ear.
“I can’t—it’s too—”
“You can.” One of his hands came up, calloused fingers wrapping around her forearm. His touch was like a live wire. “Stop fighting it. Stop holding it back.”
His other hand splayed across the small of her back, holding her steady. His skin was searing against hers. The thrum inside her became a vibration, a building pressure that made her muscles tremble. Orange light, faint at first, then brighter, began to pulse under the skin of her arms, tracing the paths of her veins like liquid embers.
She was losing control. The power was answering a call she hadn’t meant to make, fueled by the minerals, his proximity, his demanding presence. A low moan was torn from her throat as the energy crested, a silent, contained inferno raging just beneath her skin.
“That’s it,” Katsuki growled, his face close to hers. His red eyes were blazing, reflecting the light now glowing from her body. His thumb stroked over the pulsing, luminous vein on her arm, a gesture that was both clinical and intensely possessive. “That’s what I’ve been waiting to see. Show me how badly you want to survive.”
His words were the final key. The dam broke.
Fire erupted from her. Not in a wild explosion, but in a roaring, controlled cascade that flowed over her skin like a second, incandescent layer. It didn’t burn her. It didn’t scorch the rock. It simply was, a manifestation of her will, her life force, radiant and fierce. The steam around them hissed and boiled away, creating a temporary pocket of clear, superheated air.
She was panting, her body writhing against the rock, held in place only by his unyielding grip. The power was ecstasy and agony, a return and a reckoning. She looked at him, her amber eyes wide, the pupils dilated with shock and raw sensation.
He didn’t flinch. He watched the flames dance over her shoulders, down the curve of her spine, his expression one of grim, triumphant satisfaction. “There she is.”
Slowly, the cascade receded, pulling back into her skin until only the faint, pulsing glow remained in her veins, and then, finally, that too faded. The ordinary steam returned, curling around them once more. The only sound was her ragged breathing and the frantic thumping of her own heart.
His grip on her arm loosened, but he didn’t let go. His hand on her back remained.
“The water,” she breathed, the realization dawning. “It… it jump-started something.”
“It’s a catalyst. It lowered the barrier.” His voice was rough, but quieter now. “Your body just needed a push.”
They stayed like that for a long moment, pressed together in the healing water, the tension shifting from one of conflict to something else, something charged and unspoken. The line between his professional assessment and something more personal had blurred into nothing.
Finally, he released her, stepping back. The space where his body had been felt suddenly, profoundly cold.
“Don’t get used to it,” he said, the familiar gruffness returning to his voice, though it lacked its usual edge. “This is a tool. Not a cure. We use it. We understand it.”
He turned and moved back to his side of the pool, the water swirling around his waist. He didn’t look back at her.
Nala slid down until the water covered her mouth, letting the warmth hold her. The cold emptiness was gone, replaced by a humming, vibrant fatigue. She curled her fingers into fists beneath the surface, feeling the residual heat thrumming in her palms. It wasn't a permanent fix. He was right. It was a tool.
But for the first time since the diagnosis, it was a tool she could actually hold. And he had been the one to force it into her hands. She watched the rigid line of his back, the steam coiling around his shoulders, and knew the balance of everything between them had just been irrevocably shattered.
The rigid line of his back was a fortress she didn’t know how to breach. Steam clung to the defined muscles of his shoulders, a veil over the very real distance he’d just created. She felt simultaneously raw and powerful, her skin humming with a latent energy she’d thought was lost forever.
“So,” she started, her voice cutting through the thick, sulfur-scented silence. “A push?”
He didn’t turn. “You were a flicker in a windstorm. I stabilized the fuel source.” He gestured vaguely at the water around them. “And the environment.”
“By pinning me to a rock.”
“It worked, didn’t it?” He finally glanced over his shoulder, his crimson gaze a quick, searing touch. “Your method wasn’t exactly getting results, Princess.”
The old nickname, usually a barb, felt different now. It carried the memory of his growl in her ear, his hands on her skin. She sank a little deeper, the milky water hiding the flush she felt rising on her chest. “Don’t call me that.”
A faint, almost imperceptible smirk touched his lips before he turned away again. “Whatever you say.”
They lapsed back into silence, but it was a different kind of quiet now. The jungle around them seemed to hold its breath, the only sounds the gentle lap of water and the distant, subterranean rumble that vibrated through the rock beneath them. Nala focused on the feeling inside her, the warm, coiled presence where there had been only cold absence. It was a fragile thing, a fledgling power she was terrified of crushing.
“It’s not stable,” she admitted, the words quiet. “It feels… thin. Like it could snap.”
“Then we don’t let it.” He shifted, the water sloshing around him. “We use this place. We train. We figure out the limits.”
“Train? With what goal? To be slightly less helpless when the rescue ship comes?”
“The goal is to not die before the rescue ship comes,” he shot back, his voice sharpening. “Or did you already forget the things making noises in the dark? This isn’t a spa vacation. It’s a mission. Your quirk is an asset. My job is to manage assets.”
His words were deliberately clinical, rebuilding the wall between them brick by brick. She knew this game. It was one they’d played for years. Pushing him now would be useless. So she changed tactics, a small, testing probe.
“Fine. Then as your asset, I’m hungry. My muscles don’t feel like overcooked noodles anymore, they’re just regular noodles. We got anything besides sarcasm to eat?”
He let out a short, sharp breath that was almost a laugh. “There’s fruit further up the slope. Looks weird, but the birds were eating it. Probably not poisonous.”
“Probably?”
“You want a five-star review, go find a different island.” He pushed himself up and out of the water in one fluid motion, water streaming from his body. He didn’t bother covering himself, just grabbed his pants and started pulling them on over damp skin. “We’re moving. Now that you’re not about to pass out, we can make the ridge before sunset.”
The loss of the water’s warmth was immediate. A chill skated over her skin, raising goosebumps. The newfound heat inside her flickered in response, a subconscious reaction to the sudden cold. She watched him dress, his movements efficient and utterly without self-consciousness. He was all stark lines and focused intent, a weapon constantly being honed.
She climbed out after him, the air cool on her wet bra and underwear. She wringed her long hair out, the dark red strands plastered to her back and shoulders. As she reached for her own clothes, she caught him looking. It wasn't a leer; it was an assessment, a quick, calculating glance that took in her posture, the color in her skin, the absence of a tremor in her hands.
“What?” she asked, pulling the damp tank top over her head.
“Nothing.” He turned, slinging his makeshift pack over his shoulder. “You look less like a ghost.”
It was the closest thing to a compliment he would ever give. She filed it away, a small, strange warmth that had nothing to do with her quirk spreading through her chest. She finished dressing, the fabric clinging unpleasantly, but the lingering sensation of power made the discomfort trivial.
He was already heading for the tree line, not waiting for her. But he paused, just for a second, and glanced back. “Keep that ember going, Kono. Don’t let it die again.”
Then he was gone, swallowed by the green. Nala took one last look at the steaming pool, the place where her dying ember had roared back to life under his demanding hands. She curled her fingers into a fist, feeling the promise of heat just beneath the surface. He was right. It was a tool. A weapon. And for the first time, she was eager to learn how to use it again. She followed him into the shadows, the ground feeling more solid under her feet than it had in weeks.
She followed him into the shadows, the ground feeling more solid under her feet than it had in weeks. The dense canopy overhead wove a ceiling of shifting green light, and the air was thick with the smell of damp earth and decaying blossoms. Katsuki moved like a phantom ahead of her, his form a blur of purposeful motion between the trees.
“So, these probably-not-poisonous fruits,” Nala called out, her voice cutting through the jungle’s hum. “Are we talking ‘weird’ like a durian, or ‘weird’ like it has eyes?”
“They’re purple and spiky. The birds love them.” He didn’t break stride. “If you croak, I’ll note your sacrifice in my mission log.”
“How noble.” Her legs burned, but it was a clean, muscular pain, not the debilitating weakness from before. She could feel the heat from the springs still circulating in her core, a quiet engine she was terrified of stalling. “Remind me why we’re climbing up when we just found a perfectly good source of water and… other benefits.”
He stopped so suddenly she nearly collided with his back. He turned, his red eyes sharp. “Because high ground is tactical. It’s sight lines. It’s a signal fire your sputtering ass might actually be able to light now.” He gestured vaguely at her. “That little hot spring miracle isn’t a permanent fix. It’s a battery. And we’re about to drain it.”
He was right, of course. The energy was already settling, the vibrant roar subsiding into a quieter, more manageable hum. It was on loan, not a gift. She just nodded, and he turned back, pushing onward with a grunt.
The slope grew steeper, the volcanic rock crumbling under their grip. She focused on placing her hands and feet, on the rhythm of her breathing, on keeping that internal ember alive. It was a delicate, conscious effort, like balancing a spinning plate on a stick. One distracted moment and it would all come crashing down.
They broke through the tree line onto a narrow, wind-scoured ridge. The view stole the air from her lungs. The island sprawled below them, a vast tapestry of unbroken green curving around a dormant volcanic peak. The ocean stretched to the horizon, an impossible sheet of blue meeting a pale sky.
“Wow,” she breathed.
Katsuki wasn’t looking at the view. He was scanning the coastline, the layout of the land, his mind already mapping routes and resources. “There. See the river delta? Fresh water. And more of those spiky trees.”
He was all business, but she caught the way his shoulders had relaxed a fraction, the tightest coil of his tension unwound by the confirmation they weren't on some tiny, barren rock. This was a place they could survive. For a while.
“Signal fire spot?” she asked, joining him at the edge.
He pointed to a flat, bare expanse of rock near the highest point. “There. We’ll gather wood. Dry stuff from the lower canopy.” He finally looked at her, a challenging glint in his eye. “Think you can manage a controlled burn without setting the whole island on fire?”
“I guess we’re about to find out.” She offered a small, tired smile. “But first, those fruits. I’m so hungry I’d eat one even if it had eyes.”
A grunt was his only reply, but he led her to a nearby tree heavy with the strange, violet fruit. They were indeed spiky, but the spines were soft. He knocked a few down with a sharp jab of his spear, catching one and tearing it open with his hands. The inside was a startling, vibrant orange.
“Here.” He shoved a half toward her.
She took it, their fingers brushing. A static jolt, small but undeniable, passed between them. She ignored it, focusing on the fruit. It smelled sweet, almost like a mango. She took a cautious bite. The flavor exploded on her tongue—tangy and rich and utterly delicious.
“Oh my god,” she mumbled through a full mouth. “This is amazing.”
“Told you.” He was already devouring his own portion, juice dripping down his chin. He wiped it away with the back of his hand, his eyes never leaving the surrounding jungle. “Eat fast. We have work to do.”
They ate in silence, the shared simplicity of the meal feeling more intimate than the steamy confrontation in the pool. The sun warmed their skin, and for a few minutes, the relentless pressure eased. She could almost pretend they were just on a rugged hiking trip.
The illusion shattered when he stood, dusting his hands on his pants. “Okay. Fire time.” He’d already gathered a small pile of dry twigs and moss in the center of the bare rock. “Start small. Like in the water. Just a spark.”
Nala knelt before the pile, the familiar anxiety twisting in her gut. This was different. The spring had been a catalyst, its energy propping hers up. This was just her, the dry tinder, and the fragile thing inside her. She took a deep breath, trying to summon the feeling from the pool, the memory of his hands on her arms.
Nothing.
She clenched her fists, frustration bubbling up. “It’s not working.”
“Stop trying to force it.” His voice came from just behind her shoulder. He wasn’t touching her, but his presence was a physical pressure. “You’re thinking about it. Don’t think. Feel. Remember the heat.”
She closed her eyes, blocking out the vista, the wind, everything but the memory of mineral heat and his demanding growl. She let the sensation of power washing over her skin replay in her mind. The surrender. The control that came from letting go.
A wisp of smoke curled from the moss.
Her eyes snapped open. A single, bright ember glowed in the center of the nest, pulsing with her heartbeat. She cupped her hands around it, sheltering it from the wind, feeding it not with raw power but with focused intent. It caught, flames licking hungrily at the dry twigs.
A real fire. Her fire.
She let out a shaky breath she didn’t realize she’d been holding. The small flame grew, crackling confidently. She looked up at Katsuki, a genuine, unguarded smile breaking through her exhaustion.
He wasn’t smiling. He was watching the fire, then her face, his expression unreadable. “Took you long enough,” he muttered, but there was no heat in it. He turned away to gather more wood, but not before she saw it—a flicker of something in his eyes that wasn’t triumph or assessment. It was quieter. Deeper.
The fire popped and spat, climbing higher. She stayed kneeling, feeding it carefully, feeling its heat mirror the warmth still burning within her. They had a signal fire. They had food and water. They had a fighting chance.
And she had, for the first time, a glimpse of the man behind the mission. The realization was as unsettling as it was compelling, a new kind of spark taking root in the dark, fertile soil of their shared isolation. She watched his back as he worked, the sun catching the blonde of his hair, and knew nothing would be simple again.