The lie settled into the marrow of her bones, a cold, dense thing she carried with her into the small, sterile bunk attached to the lab. She slept fitfully, her dreams a chaotic swirl of iridescent dust and the phantom scent of alien blossoms. When she woke, the first sensation wasn't fear or remorse, but a thirst so profound it felt like her entire body had been desiccated from the inside out. It was a cellular scream for water.

Her throat was a desert, her tongue a thick, clumsy thing in her mouth. She stumbled to the small kitchenette, grabbing a bottle of water and draining it in one long, desperate pull. The cool liquid didn't just slide down her throat; she could almost feel it being wicked away by the tissues of her esophagus, absorbed before it even hit her stomach. It wasn't enough. She drank another, and then a third, the plastic crinkling in her tight grip. The ache in her cells subsided from a shriek to a dull, persistent thrum. It was a new baseline: a deep, insatiable need that normal hydration couldn't touch.

Throughout the day, she kept a two-liter bottle at her side, refilling it constantly. David watched her, his dark eyes missing nothing. “You trying to set a new record?” he asked lightly, his voice carefully casual as she returned from the water cooler for the fourth time that morning.

“Just dehydrated,” she mumbled, avoiding his gaze. “The recycled air in here… after the lockdown… it’s dry.” Another lie. The lab’s environmental controls were perfect. The air was no drier today than it had been yesterday. But the thirst was a physical master, a demanding presence that overrode logic.

By the second day, the other craving began. It was a subtler thing, not a desperate ache but a slow, inexorable pull. The main biolab was a windowless vault, its light a constant, sterile white from the overhead LEDs. But connected to it was the terrestrial solarium, a small glass-domed room where they cultivated control samples of Earth flora. It was the only place in their sealed world that received direct, unfiltered sunlight.

Sage found herself drifting toward it, drawn by an instinct she couldn't name. She’d stand at the sealed doorway, looking in at the lush green ferns and sturdy oaks, her eyes fixed on the brilliant shafts of sunlight piercing the dome. The pull was magnetic.

On the third day, she gave in.

Claiming she needed to check the irrigation sensors on the control group, she entered the solarium. The air was warm and humid, thick with the smell of damp earth and chlorophyll. But it was the light she craved. She walked directly into a wide, golden patch of it, stopping in the center of the beam. She tilted her head back, closing her eyes, and let the unfiltered sunlight wash over her face and neck.

It was more than warmth. It was a feeling of being plugged in, of a current flowing directly into her skin. The persistent, low-grade prickling that had been her constant companion since the breach—the sensation she’d been desperately trying to ignore—seemed to quiet under the sun’s glare. It didn't disappear, but the frantic, irritating energy was soothed, transformed into a deep, humming vibration of pure vitality. It felt like drinking, but not with her mouth. She was absorbing it, every pore on her exposed skin opening like a thirsty mouth, taking in the light and heat with a greed that was terrifying and ecstatic.

She stood there for what felt like an eternity, motionless, a strange heliotropic statue in a lab coat. She was so lost in the sensation, in the feeling of her very cells plumping with this strange, new energy, that she didn't hear David enter.

“Sage?”

Her eyes snapped open. He was standing by a row of potted gingko trees, a data-slate in his hand, his brow furrowed with a concern he no longer bothered to hide. “Everything okay with the sensors?”

“Fine,” she said, her voice a little too breathy. She stepped out of the sunbeam, and the loss was immediate, a sudden unplugging that left her feeling empty and cold. The prickling itch returned, a faint but insistent reminder under her skin. “Just… enjoying the warmth for a second. It’s freezing in the main lab.”

David didn’t look convinced. His gaze lingered on her face, on her neck, on the sliver of skin visible at her open collar. He said nothing, but his eyes were analytical, searching, as if trying to solve an equation that didn’t add up. The thirst, the constant exhaustion she tried to hide, and now this… this strange, sun-worshipping behavior. It wasn't Sage. Not the Sage he knew. He watched her walk past him, her movements stiff, and for a second, just as a beam of light caught the side of her neck, he thought he saw it. A faint, almost imperceptible shift in her complexion. A healthy glow that wasn’t just a flush. It was a color that didn't belong on human skin.

It was a trick of the light. It had to be. A reflection from the dense foliage, the emerald glow of the moss beds casting an illusion upon her skin. David stood frozen for a moment after she left, the warm, humid air of the solarium feeling suddenly oppressive. He repeated the rationalization in his head, a mantra against the rising tide of impossibility. But the explanation felt thin, a flimsy shield against what his eyes had registered. It hadn’t been a surface reflection. It had been an emanation, a soft, vital light shining from beneath the surface, the color of a freshly unfurled leaf.

He followed her back into the main lab, his movements stiff. He tried to immerse himself in his work, to focus on the spectral analysis of the quarantined chamber, but his gaze kept drifting to her. Under the sterile, white glare of the overhead LEDs, the phenomenon was far less pronounced. Her skin was still pale, still Sage. But now that he was looking for it, he could see it. It was in the subtle hollow of her throat, in the delicate skin of her inner wrist as she typed. It wasn't green like a reptile or an amphibian, but a faint, luminous undertone, as if her very blood was being slowly infused with chlorophyll. It gave her a strange, ethereal vitality, a look of impossible health that was profoundly unnerving.

The next day, his observation became more deliberate, a covert study he kept hidden behind a mask of professional normalcy. He found an excuse to recalibrate the lighting at her workstation, cycling through different temperatures of light. Under the warmer, yellower tones, the green tint was almost invisible, swallowed by the gold. But when he switched to the cooler, bluer spectrum, it emerged, a clear, distinct undertone that made the hairs on his arms stand on end. She shot him an irritated look. "Is there a problem, David? It’s like a disco over here."

"Just checking the kelvin consistency," he lied, his voice tight. He quickly set it back to the standard white.

His unease solidified into cold dread that night. Unable to sleep, he sat in the dark of his bunk, his data-slate glowing. He pulled up their project’s video logs, skipping back a few weeks. There she was on the screen, her face animated as she debated a complex protein model with him. Her skin was its familiar ivory, prone to flushing pink when she was excited or angry. He swiped to the security footage from that afternoon, capturing her standing by the water cooler, her back to the camera. He zoomed in on the nape of her neck, just below her hairline.

He placed the two images side-by-side. The Sage from three weeks ago and the Sage of today. The difference was subtle, yet stark and undeniable. The faint, almost translucent quality of her skin had been replaced by something with more depth, more… substance. And the color, a verdant whisper beneath the pale tones of her complexion, was there. It wasn’t a sign of sickness. In fact, it looked the opposite. It was the vibrant, living green of new growth.

He shut the slate off, plunging his room into darkness. The silence of the lab complex pressed in on him. This was not an allergic reaction. This was not a dermatological anomaly. This was assimilation. The alien spores hadn't just been inhaled; they had planted themselves in her, and now they were beginning to sprout. His scientific mind reeled from the sheer biological heresy of it, but his gut clenched with a simpler, more primal fear. He was watching the woman he knew, the brilliant, infuriating, wholly human woman who was his partner, being rewritten molecule by molecule. The line between professional concern and personal terror had just been erased.

The next morning, David cornered her by the chromatography station, blocking her path with a deliberate gentleness that was more unnerving than an order. “Sage. I need to run a few diagnostics.”

“Diagnostics for what?” she asked, her tone brittle. She clutched a water bottle like a shield. “I’m fine, David. A little tired.”

“It’s a follow-up precaution from the breach,” he said, his voice level and calm, a carefully constructed lie. “A full-spectrum dermal analysis, vitals check. Standard procedure for any potential contaminant exposure. I should have done it days ago. My mistake.”

She wanted to refuse, to tell him to fuck off, but the cool logic of his words offered a plausible excuse, a way to submit without admitting her own terror. To argue would be to acknowledge that something was truly wrong. “Fine,” she clipped out. “But make it quick. I have to finish calibrating the sequencers.”

He led her to the small med-bay alcove, the air suddenly thick with unspoken tension. He didn't ask her to undress, just to sit on the edge of the examination bed. First, he clipped a pulse oximeter to her finger. The small red light glowed against her nail bed. He watched the monitor, his face impassive. Her heart rate was a slow, steady 52 beats per minute, as calm as a deep-sea creature in the crushing dark. Her oxygen saturation was a perfect, unwavering 100%. Too perfect. She wasn't breathing deeply, yet her blood was super-saturated with oxygen.

“Breathe normally,” he murmured, his voice low. He reached for the full-spectrum dermascope, a handheld device that looked like a futuristic magnifying glass. “I’m just going to scan your neck and arms. Standard procedure.”

His hand came up to steady her, his fingers resting on her shoulder. His touch was clinical, yet it sent a shiver through her that had nothing to do with the cold. She could feel the warmth of his palm through the thin fabric of her shirt, a stark contrast to the strange coolness of her own skin. He brought the scope close to her neck, the lens hovering just a millimeter from her flesh. She held her breath, watching his face. His eyes, magnified by his own glasses, were dark and intense, focused entirely on the landscape of her skin. He was so close she could smell the faint, clean scent of his soap mixed with the sterile aroma of the lab.

He didn't speak for a full minute, just slowly moved the scope across her collarbone, down her arm to her wrist. She could see the readouts on the device’s small screen—a cascade of complex graphs and chemical signatures she couldn't decipher from her angle. But she could see the line of his jaw tighten.

“What?” she finally whispered, her voice tight. “What do you see?”

He pulled back, his expression a mask of neutrality. “The pigment concentration is anomalous.” He chose his words carefully. “There are chromatophores in the dermal layer that don’t match any known human cellular structure. They’re… highly efficient at absorbing light in the 400 to 700 nanometer range.”

“In English, David.”

He met her gaze, and for the first time, she saw the professional mask crack, revealing the raw fear beneath. “They look like chloroplasts, Sage. But the energy signature is alien. It’s not producing glucose. It’s producing… something else. Something the scanner can’t identify.”

A cold dread, colder than her own skin, washed through her. Chloroplasts. The word hung in the air between them, an obscene impossibility. She felt a desperate urge to be in the sun, to feel that warmth, that energy, that feeding.

David put the scope down and picked up a thermal imaging camera. He scanned her body, and the screen lit up in a swirl of color. Most of her was a cool blue-green, but the areas where he’d noted the green undertone—her neck, her wrists, the delicate skin behind her ears—were a deep, cold violet. Far cooler than the rest of her body.

“You’re running cold,” he stated, his voice flat with disbelief. “Metabolically, you should be a furnace. But these areas… it’s like they’re actively drawing heat from the environment instead of producing it.”

Every piece of data was a new verse in a biological horror story. She was exhaling pure oxygen. Her skin was drinking light. She was becoming… a plant. The thought was so insane she almost laughed. But looking at David’s grim face, the sound died in her throat.

The tests were over, but the space between them remained charged, the sterile air thick with the results. The data proved nothing and everything. It offered no diagnosis, no cure, only confirmation of the impossible. The mystery had deepened, coiled itself around them in the silent, humming lab. David stood staring at the screen of incoherent, terrifying data, a scientist facing the utter failure of his science. Sage wrapped her arms around herself, a sudden, profound chill settling into her bones. The professional line they had always maintained had not just been blurred; it had been vaporized, leaving them standing on opposite sides of a terrifying new reality, bound together by a secret that was growing right under her skin.

He reached out and switched off the thermal camera’s monitor, plunging the screen into darkness. The damning evidence vanished, but the truth of it remained, hanging between them like a physical weight. The silence stretched, thick and suffocating, until David finally broke it. His voice, when he spoke, was stripped of all scientific detachment. It was just him.

“Okay,” he said softly, his gaze fixed on her face, not on a data point or a readout. “Okay, Sage.”

The repetition, the quiet finality of it, was more terrifying than any clinical diagnosis. It was an acceptance of the unbelievable. He wasn't her research partner anymore, not in that moment. He was the sole witness to her metamorphosis, the only other person on the planet who knew she was becoming something other.

In the days that followed, the lab’s atmosphere changed. The frantic, data-driven energy was replaced by a quiet, watchful tension. David abandoned any pretense of running further tests. The data was irrelevant now; her survival was not. His concern manifested in a series of small, unspoken actions. He rerouted the power conduits to the main arboretum, intensifying the full-spectrum lamps until the room glowed with the ferocity of a midday sun. He’d find reasons for her to go in there with him. “I need you to double-check the soil pH for the xenoliths,” he’d say, a flimsy excuse they both silently accepted.

He kept a constant supply of chilled, purified water on her desk, replacing the bottle before it was ever empty. When he saw her unconsciously leaning toward the blue-white glare of her monitor, he would quietly adjust the overhead light panel above her station, increasing its intensity and shifting the spectrum to mimic natural daylight.

At first, Sage bristled at the silent coddling. Every glass of water felt like an admission of weakness, every suggestion to enter the sun-drenched arboretum a reminder of her monstrous transformation. She was Dr. Sage Greenwood, a brilliant mind, not some… houseplant that needed tending. But her body betrayed her pride. The thirst was a physical ache, a deep-seated craving that plain tap water couldn’t quench. The pull toward the light was a magnetic, cellular-level command. She would find herself standing in the artificial sunlight of the arboretum, eyes closed, feeling the energy soak into her skin, and know that David had orchestrated it. Her resentment warred with a desperate, shameful gratitude.

The shift crystalized late one night. She’d been at the gene sequencer for twelve hours straight, determined to find a flaw in its programming, a rational explanation that wasn’t her. But the lab’s standard lighting felt dim, suffocating. A wave of profound exhaustion washed over her, so sudden and complete it was like a switch had been flipped. The world tilted, the glowing screen dissolving into a blurry smear. Her head grew heavy, and she slumped forward, her cheek hitting the cool metal of the console.

She didn’t hear him approach, but she felt his presence, a sudden warmth cutting through her deep chill. A hand landed on her back, firm and steady. “Sage.”

She tried to push herself up, to mutter something about being tired, but the effort was too much. David’s hand slid from her back to her arm, his fingers wrapping around her bicep. He gently pulled her upright.

“That’s enough,” he said. His voice was not a suggestion. It was a soft command, laced with an authority she had never heard from him before. He didn’t guide her toward the med-bay or her bunk. Instead, he led her away from the workstations, toward the glowing doorway of the arboretum.

He didn’t let go of her arm until they were standing in the center of the room, bathed in the brilliant, life-giving light. The warmth sank into her skin instantly, a soothing balm on a raw wound. The dizziness receded, the profound weakness easing its grip. He didn't speak, just stood beside her, a silent guardian. The air was warm and humid, smelling of rich soil and alien flora. For a long moment, they just stood there, breathing.

Finally, Sage leaned sideways, a small, almost imperceptible movement, until her shoulder rested against his. It was a concession. An admission. A surrender. He didn’t flinch or pull away. He simply stood with her, solid and present, sharing the light. In the silent, vibrant greenhouse, surrounded by impossible life, the last vestiges of their professional relationship withered and died, making way for something far more complicated, and infinitely more human.