The Xenobiologist's Mate Bond

• Chapter 1 Fieldwork on Xylos
• Chapter 2 The Native Guide
• Chapter 3 Bioluminescent Warning
• Chapter 4 Spores and Protocol
• Chapter 5 The Resonance Pulse
• Chapter 6 Incompatible Readings
• Chapter 7 Unscheduled Fusion
• Chapter 8 Symptoms of the Bond
• Chapter 9 Scientific Denial
• Chapter 10 Shared Sensations
• Chapter 11 Deep in the Canopy
• Chapter 12 Biolinked Hearts
• Chapter 13 The Elders' Lore
• Chapter 14 No Known Antidote
• Chapter 15 A Guide's Devotion
• Chapter 16 Night of the Spore Storm
• Chapter 17 Thermal Drift
• Chapter 18 Whispers in the Blood
• Chapter 19 Laboratory Protocol Breach
• Chapter 20 Conflicting Instincts
• Chapter 21 The Canopy Falls
• Chapter 22 Symbiotic Surrender
• Chapter 23 The Colony's Ultimatum
• Chapter 24 Irreversible Chemistry
• Chapter 25 Bound to the Wild
• Chapter 26 Two Worlds, One Pulse

The atmospheric moisture index of Xylos sat at an oppressive ninety-eight percent, which meant Dr. Mara Perez had spent the last three hours feeling like a poached dumpling inside her field environment suit.

She paused on a moss-slicked root system the size of a mag-train fuselage, braced one bootsolenoid against the fibrous bark, and adjusted the optical spectrum visor clamped across the bridge of her nose. The glass flashed iridescent teal, cycling through infrared, ultraviolet, and finally settle-focusing on the narrow band of bio-resonance emissions she had flown four light-years to document.

"Specimen forty-two," Mara dictated into the pin-mic seated beside her jaw. Her voice was flat, rhythmic, and stripped of the sheer physical misery her sweat glands were currently undergoing. "Sub-canopy fungal cluster, genus tentative: Pseudoscypha radiata. Diameter approximately eighteen centimeters. Substrate is the decaying cambium of a primary tier iron-fern. Ambient temperature is thirty-two degrees Celsius. Chemical composition of the surrounding mulch shows high concentrations of sulfurous esters and trace neuro-reactive alkaloids."

She drew a micro-scalpel from the hard-cased equipment bandolier crossing her chest. Her suit, standard United Earth Colonial Science Division issue, was colored a blinding, institutional hazard-orange. It made her look like a piece of industrial machinery that had been accidentally dropped into a primeval Eden, which suited Mara just fine. Nature on Earth was something civilized people managed in municipal greenhouses or admired through sterilized observation glass. Out here, nature was a wet, suffocating tangle of uncataloged metabolic pathways that actively wanted to dissolve her boots.

A fat, indigo water droplet fell from a frond seventy feet above her, striking the crown of her reinforced helmet with a hollow thunk. Mara didn't flinch. She had cataloged sixty-one distinct species of vascular undergrowth in this single square kilometer of the low-basin rainforest over the past week, and every single one of them wept sticky, resinous fluids.

With mechanical precision, she scraped a gossamer shaving from the mushroom’s underside. The fungal specimen didn't bleed sap; it pulsed. A low, rhythmic ripple of sapphire light chased itself around the outer rim of the cap, vibrating at a frequency so low it registered more as an itch in the fillings of her molars than an audible sound.

"Bioluminescent activation occurs upon mild physical trauma," she added, watching the sample container slide shut with an airtight hiss. The specimen vial automatically chilled to negative four degrees, flash-freezing the tissue’s intercellular matrix. "Luminescence is accompanied by an electro-chemical discharge of approximately twelve millivolts. No external spore dispersal noted during extraction. The organism appears to operate on a closed-circuit cellular cycle, likely reliant on host-tree vascular rhythm."

Mara logged the coordinate data on her wrist terminal. The datapad’s screen had a thin smudge of iridescent pollen along its lower bezel—no matter how meticulously she disinfected the perimeter seals of her research station airlock, the planet found a way to deposit its glittery junk onto her equipment.

She checked the local chronometer. It read 14:10 Terran Standard, which meant she had exactly fifty minutes before the secondary sun, Xylos-Beta, dipped behind the mountain range to the west. Once the second sun set, the planetary canopy shifted its gas exchange phase. The vegetation stopped exhaling relatively benign oxygen-nitrogen mixtures and began purging heavy hydrocarbon vapors that turned the air into an opaque, hallucinogenic pea-soup.

Regulations clearly stated that unassisted solo researchers were to be back within the perimeter fence of Expedition Base Alpha three hours before dusk. Mara had already blown past that deadline by two hours and fifteen minutes, but the expedition’s director, Dr. Aris Thorne, was currently ninety miles up in orbit on the station shuttle arguing over shipping manifests with colonial bureaucrats. As long as Mara produced clean, peer-reviewed data on the forest's symbiotic networks, Thorne rarely bothered to check the time stamps on her field excursions.

She shouldered her heavy field pack, the kinetic frame humming as its micro-servos compensated for the weight of thirty pounds of cryo-jars and soil augers.

The low-basin jungle hummed around her, a constant, layered thrum that sounded like an orchestral tuning session gone horribly wrong. Overhead, the canopy soared to heights exceeding four hundred meters. The trees on Xylos didn’t grow like Earth trees; they didn't taper or branch into orderly canopies. Instead, massive, fibrous columns wound around one another in colossal braids, fusing at irregular junctions to form an unbroken wooden roof that blocked ninety percent of direct sunlight.

Down on the floor, in the perpetual twilight, life thrived on symbiosis. Everything touched everything else. Vine-like tendrils bound ferns to roots; translucent mosses grew directly into the chitinous carapaces of sluggish, six-legged millipedes; and everywhere, pulsing through every crack and crevice of the black soil, ran the mycelial webs.

Mara stepped off the root and sank ankle-deep into a bed of damp, purple liverwort. The ground exhaled a sweet, sharp smell like crushed cinnamon and ammonia.

"Movement along transect seven," she murmured, scanning the path ahead.

Her field terminal beeped an alert. A high-gain biological ping had registered approximately eighty meters to the southeast, deeper in the gully where the iron-ferns gave way to the dense, black-barked stands of ribbon-wood.

Mara stopped. She touched the control dial on her chest pack, bringing up the localized bio-scans. The expedition’s base camp had identified hundreds of non-sentient fauna species in this sector—most of them venomous, several of them large enough to view an armored human as a crunchy protein bar, but none that typically registered this high on the neuro-electrical density spectrum.

The reading wasn't the frantic, scattered scatterplot of a startled jungle beast. It was rhythmic. Deliberate. A smooth, coherent wave that rose and fell in time with the ambient resonance of the forest itself.

"Base Alpha, this is Field Unit Three," Mara said, tapping her comm link.

Static hissed in her ear. A burst of planetary interference, thick with the atmospheric ion-bleed caused by the twin suns, crackled over the line.

"...Perez... repeat... signal breaking... return to perim..."

"Base Alpha, signal degraded. I have an anomalous neural-density ping eighty meters southeast of my designated collection grid. I am proceeding to verify before RTB."

The comm didn't answer, only giving back the dry frying-pan crackle of the ionosphere.

Mara didn't wait. If she returned to base without identifying the anomaly, Thorne would inevitably assign the follow-up survey to Dr. Henderson, a man whose scientific methodology consisted largely of dropping robotic probes into the dirt and complaining about the humidity from the air-conditioned interior of a crawler. Henderson wouldn't know a significant symbiotic mutation if it bit through his utility belt.

She pulled a high-tensile sample rod from her side pouch, twisting the locking mechanism until the titanium-alloy spike clicked into place. It was technically a geological tool, but the sharp, weighted tip made an adequate defensive spear if something with too many mandibles took an interest in her calves.

Mara moved through the ferns, her gait practiced and careful. She kept her weight centered over the balls of her feet, avoiding the slick patches of orange slime-mold that carpeted the limestone boulders. The light between the braided trunks was changing. As Xylos-Beta sank toward the horizon, the daylight shifted from a pale, brassy gold to a deep, oceanic violet.

The forest responded immediately. Phosphorescent veins along the bark of the ribbon-woods began to flare, waking up in shades of emerald, amber, and electric cobalt. It was a chemical reaction triggered by the drop in light intensity—luciferin analogues reacting to ambient atmospheric cooling. Mara had written a sixteen-page paper on the mechanics of it two months ago. It was purely biochemical, entirely functional, and had nothing whatsoever to do with the "mystical spirit of the woods" the civilian trade reps liked to babble about after three drinks at the outpost commissary.

She pushed past a curtain of hanging aerial roots that felt like cold, wet rope against her gauntlets.

Before her, the terrain sloped sharply downward into a narrow limestone sinkhole. At the bottom of the depression, the ground was cleared of underbrush. Instead, the floor was covered in an unbroken sheet of living white lichen that looked like a pool of frozen milk.

In the center of the lichen sheet stood an organism that made Mara’s fingers freeze on the record button of her datapad.

It was an anemone-tree, or what the preliminary surveys classified as Dendractis carnea. The trunk was flesh-pale, rubbery, and stood no taller than a human. In place of branches, it possessed a crown of hundreds of translucent, ribbon-like tentacles that swayed through the still air with hypnotic grace. Each tentacle was tipped with a teardrop bulb of violet luminescence that pulsed in sync with the forest's deeper frequency.

Standing less than two paces from the tree was a person.

Mara’s breath hitched in her throat, fogging the corner of her optical visor for a brief second before the internal heaters cleared it.

The figure was native. An inhabitant of Xylos, one of the indigenous humanoids the colonial administration had designated as the Kaelen, though the settlers colloquially referred to them simply as the Foresters. Base Alpha had had minimal contact with them; the native tribes avoided the steel-and-plasteel footprint of the human settlement, treating the researchers with a silent, distant indifference that bordered on contempt. What little the Science Division knew of them was compiled from long-range drone footage and third-hand accounts from frontier scouts.

This native was tall—easily half a foot taller than Mara’s own five-foot-seven—with broad, tapered shoulders and the lean, corded musculature of someone built to move through high-canopy limbs. His skin was a deep, dusk-colored bronze that carried an iridescent, pearlescent sheen under the violet light, as if microscopic silica crystals were embedded in the dermal layers. Along the ridges of his collarbones and tracing the lean contours of his arms ran faint, branching lines of soft, bioluminescent turquoise that matched the ambient pulse of the surrounding flora.

He wore no environment suit. He wore virtually nothing at all save for a wrap of dark, treated hide around his hips and high, supple gaiters of woven plant fiber that bound his calves. No respirator. No filters. He stood in the middle of a toxic hydrocarbon sinkhole, breathing the unrefined planetary air as if it were mountain spring water.

Mara remained entirely motionless behind the hanging roots. Her analytical mind surged into overdrive, cataloging details with furious efficiency.

Subject: Male Kaelen. Age indeterminate. Dermal luminescence active, indicating stable bio-electrical synchronization with local flora. Respiration steady, deep, approximately eight cycles per minute. Unprotected exposure to high-concentration spore plume.

The man had his eyes closed. His face was angular, with high, sculpted cheekbones, a straight, prominent nose, and a strong, square jaw that was set in an expression of deep, serene concentration. His hair was long, black as carbon-slik, bound back from his temples with thin cords of twisted bark, revealing slightly pointed ears that swiveled independently toward the faint rustle of the canopy above.

He was reaching out.

One bare, long-fingered hand was extended toward the central tentacles of the anemone-tree. The tips of his fingers hovered bare millimeters from the glowing violet bulbs. The plant wasn't retreating; rather than pulling away or lashing out with the paralytic neurotoxins Mara knew the tentacles contained, the organism was leaning toward him. The pale, fleshy ribbons coiled gently around his wrist, pulsing with bright, rhythmic waves of indigo light that seemed to mirror the turquoise veins glowing beneath the man’s skin.

It was an active, real-time bio-feedback loop.

Mara’s fingers twitched on her datapad. The implications were staggering. Expedition Alpha had operated on the hypothesis that the indigenous population merely navigated the ecosystem using specialized olfactory cues and instinctual territorial knowledge. No one had documented direct, real-time physiological interfaces between a sentient native and the toxic, non-sentient sub-flora. This wasn't primitive navigation; this was bio-resonance communication. It was an inter-species neural bridge.

If she could record the exact harmonic resonance of that interface—if she could measure the millivoltage and isolate the neuro-chemical transfer agents occurring at the dermal junction—she would have the foundational paper of her career. It would silence Thorne’s snide remarks about her over-reliance on laboratory isolation. It would rewrite the entire colonial protocol on native relations.

She slowly shifted her weight to bring her high-resolution spectro-scanner to bear through the gap in the vines.

Her right boot settled into the mulch.

Beneath the carpet of purple liverwort lay a hollow root chamber, rotten and brittle from years of internal fungal decay.

The wood gave way with a sharp, dry crack that sounded like a gunshot in the silent sinkhole.

Mara’s foot plunged six inches into the cavity. Her knee locked, the sudden drop throwing her kinetic pack off-balance. She caught herself against the rough trunk of the ribbon-wood, her armored shoulder slamming into the bark with a dull, resonant thud.

The effect was instantaneous.

The anemone-tree snapped its tentacles back into a tight, defensive knot, the vibrant violet light winking out like a snuffed candle. A sharp, whistling hiss tore through the air as the plant expelled a cloud of bright, sulfurous defense powder into the sinkhole.

The native turned.

He didn't scramble or drop into a defensive crouch like a startled animal. He moved with a terrifying, liquid economy of motion, pivoting on the balls of his bare feet to face the source of the disruption.

His eyes were open now. They were amber—not the dull brown of Terran eyes, but a vivid, molten gold with vertical, slit-like pupils that expanded rapidly in the dim violet light of the forest.

Through the clear faceplate of her helmet, Mara found herself staring straight into that golden gaze.

For three seconds, neither of them moved.

The forest around them seemed to hold its breath. The ambient hum of the canopy faded into the background, drowned out by the harsh, rhythmic rush of Mara’s own breath echoing inside her helmet. Her head-up display flashed an amber warning: ELEVATED HEART RATE: 112 BPM. CARBON DIOXIDE RECYCLER AT 88% CAPACITY.

She stood half-trapped in the rotten root, her high-tensile sample rod held awkwardly in one gauntleted hand, her high-tech hazard-orange suit screaming its artificiality against the primeval backdrop.

The native guide didn't look afraid. He didn't look angry.

He tilted his head slightly, studying her with an expression of sharp, intense curiosity. His eyes traveled from the bright orange fabric of her suit, down to the heavy, mechanical soles of her boots, and then back up to the glass visor that concealed her features.

Then, the corner of his mouth curved upward. It was a slow, knowing, distinctly amused smile that revealed teeth just slightly sharper than those of a baseline human.

He took one step toward her. The bioluminescent markings along his collarbones flickered, shifting from calm turquoise to a warmer, pulsing shade of gold that matched his eyes.

"Don't move," Mara muttered under her breath, her fingers tightening on the grip of her sample rod as she prepared to engage her suit's defensive arc-taser. "Stay right where you are."

The man didn't stop. He moved with silent, predatory grace across the white lichen floor, stepping over the toxic mulch as easily as if it were a paved terrace, his eyes locked entirely onto hers.

Mara’s survival training had been condensed into a three-week seminar in an air-conditioned bunker on Geneva Four, during which a retired quartermaster had repeatedly stressed that uncontacted xenomorphic humanoids were to be treated as high-voltage electrical conduits: dangerous, unpredictable, and best observed from behind several inches of leaded glass.

The quartermaster, however, had never been jammed ankle-deep into a bed of decomposing alien pulp while a seven-foot specimen glided toward him like an apex predator who had just spotted an unusually bright citrus fruit.

"Stand down," Mara said aloud. The exterior speaker grid of her helmet projected her voice as a flat, digitized drone that scraped through the damp air. "I am Dr. Mara Perez of the United Earth Science Directorate. Under Colonial Charter Section Nine, I am an authorized ecological observer. Remain where you are."

The native stopped two paces short of the ledge where she hung caught. He didn't drop into a stance of surrender, nor did he display the territorial bristling typical of high-metabolism mammalian hunters. Instead, he tilted his head, his slitted amber pupils dilating until only a ring of gold remained around the glossy black centers. The soft, luminous filigree along his collarbones flickered—a staccato rhythm of chartreuse and amber that mirrored the rising cadence of Mara’s breath.

"You speak a great deal of nonsense for a creature trapped in a rotten gully-root," he said.

Mara’s fingers went completely numb against the handle of her sample rod. The language was Terran Standard, though warped by an accent that dragged vowels through the back of the throat and snapped consonants with crisp, percussive clicks. His voice had an eerie acoustic depth, resonating as though his chest cavity functioned as an organic acoustic chamber.

"You speak Standard," she managed, her grip tightening until her suit’s tactile feedback sensors whined.

"The pale men at the metal village shout it through loudspeakers whenever they drop crates from the sky," the native replied. His tone was breezy, effortless, and infused with an infuriating lack of deference. "And their traders have very loose tongues when they desire dried star-moss. I am Theran. I do not usually find Directorate researchers wedged into the mulch like discarded seed-pods."

"I am not wedged," Mara lied through her teeth, hauling upward against the frame of her suit. The kinetic servos in her right knee groaned in protest. The fibrous root had collapsed inward, creating a tight, vacuum-sealed collar of fibrous wood around her shin. "I am conducting an in-situ geological assessment of sub-canopy structural integrity."

Theran crossed his arms over a chest that was broad, bare, and shockingly unblemished by the toxic brambles that tore through synthetic Kevlar. The skin along his forearms had a faint, cross-hatched texture, like the scales of an emerald viper ground down to silk. "Your sub-canopy structural integrity is currently digesting your boot, Doctor."

He stepped closer, closing the distance between them without displacing a single leaf. Up close, Mara realized he didn't smell like sulfur or the sweet, rot-tinged musk of the low basin. Her suit's external atmospheric sensor registered trace scents through its diagnostic nose-port: crushed resin, crisp ozone from high-altitude storms, and something sharply botanical, like cracked juniper berries.

"Do not approach," Mara commanded, leveling the pointed titanium tip of her sample rod at his midsection. "Base protocol forbids unsterilized physical contact. You are in violation of scientific quarantine zones."

Theran looked down at the pointed metal rod. He didn't flinch. Slowly, deliberately, he raised one long-fingered hand and tapped the sharp tip with the pad of his index finger. The contact produced a distinct, crystalline click.

"If you press that switch beneath your thumb," he remarked conversationally, glancing down at the recessed arc-taser toggle on her grip, "you will discharge thirty thousand volts into the chitin-fern beneath your left heel. The entire root system here is an electrolytic web. You will stun yourself, burn your insulation, and wake up three days from now inside the belly of a mud-crawler. But please, proceed. I find your species endlessly entertaining."

Mara froze, her thumb hovering millimeters from the red toggle. Her optical visor flickered, running a hasty conductivity scan on the purple liverwort beneath her boot. The readouts flashed violent red: high moisture, high ionic salt content, extreme galvanic conduction.

He was telling the truth. If she had fired the defense charge, the current would have grounded through her own leg.

"How do you know about Directorate shock-staves?" she demanded, refusing to lower the weapon even as she eased her finger off the ignition switch.

"I guide your people when they wander into the deep reaches and begin to cry," Theran said smoothly. He offered a small, sharp-toothed grin that made the fine hair on the back of Mara’s neck stand at attention. "Director Thorne pays me five rations of refined cobalt salt for every foolish academic I pull out of the venom-traps. Though usually, he sends me with an escort. He did not tell me he had let a solitary female loose in the singing groves."

"I do not require an escort," Mara snapped, bristling at both his assessment of her independence and the casual mention of her superior. "And Dr. Thorne has no authority to contract native guides without an interdisciplinary review board."

"Thorne is an old fool who fears the spores," Theran countered with a casual shrug that shifted the glowing lines along his shoulders. "And you, Doctor, are five minutes away from the evening breath of the ribbon-woods. Look up."

Mara didn't want to follow his direction, but her scientific training overcame her stubbornness. She tilted her helmet back.

High above, through the braided wooden rafters of the forest, the light had turned into a terrifying shade of bruised indigo. The secondary sun had slipped completely below the jagged horizon of the western crags. The thick, rubbery leaves of the upper canopy were beginning to curl inward, unsealing their underside stoma with audible, wet pops. A faint, pearlescent mist was starting to drift down from the ceiling like ghostly snow, carrying the distinct, heavy shimmer of aromatic hydrocarbons.

The evening purge had begun.

"My suit is fully sealed," Mara stated, though she checked the atmospheric regulator on her left wrist with a sudden clench in her gut. "Class Four filtration. It can handle up to three hundred parts per million of organic neurotoxins."

"The canopy does not produce three hundred parts," Theran murmured, stepping into her immediate personal space. The sheer size of him was overwhelming; he moved with an unhurried confidence that made her heavy, motorized frame feel clumsy, an obsolete relic of steel and plastic. "It produces ten thousand. And it does not merely enter through the mouth, little scholar. It seeks out synthetic seals. It eats through the petroleum gums that hold your clear mask to your neck."

He reached down, his hands moving so swiftly that Mara didn't even have time to swing her rod.

Before she could shout, his long, bronze fingers clamped onto the fibrous wood surrounding her trapped foot. He didn't pull with brute force; instead, the luminescent veins in his forearms flared with brilliant, pulsing teal light. He hummed—a deep, guttural chord produced from the base of his diaphragm that rattled the titanium diaphragm of her suit's audio pick-up.

Under his touch, the white lichen that coated the root flared in direct harmonic response. The hardened, constricting wood sighed. The fibers loosened, relaxing their grip as if responding to a biochemical password.

Theran gave a sharp upward jerk, and Mara’s boot popped free from the suction with a squelching gasp.

The sudden release sent her backward. Her kinetic pack, heavy with field jars and geological instruments, pulled her off-balance. She braced for a humiliating, bone-jarring crash onto the damp stone shelf behind her.

It never came.

A warm, solid arm caught her around the waist, arresting her fall instantly. The contact was so sudden, and his grip so immovable, that the breath punched out of her lungs.

Even through the layered, thermal-insulated fabric of her hazard suit, Mara could feel the shocking heat radiating from his body. Native physiology, according to the rudimentary scans Base Alpha possessed, ran four degrees hotter than human standard, but this felt like being pressed against a thermal radiator.

Through the thick plasteel visor, her face was inches from his.

Theran’s eyes were wide, luminous, and terrifyingly clear. He wasn't breathing hard, despite having just hauled a two-hundred-pound armored human out of a living vice with one arm. Up close, she could see tiny, crystalline specks embedded in his bronze skin that caught the gathering twilight, glittering like crushed stars across his cheekbones.

He looked down at her face, his gaze penetrating the tinted, anti-reflective coating of her helmet as easily as if it were clear water.

"You have very small eyes," Theran observed, his voice dropping into that rich, rhythmic register that vibrated uncomfortably in the center of her ribcage. "And you smell of burnt metal and fear."

Mara scrambled for purchase, planting her boots firmly on the solid limestone ledge and shoving against his chest with both gauntleted hands. It was like trying to push over an ancient stone monument.

"Release me," she demanded, her voice tight and razor-sharp.

Theran let go instantly, raising both hands with mock innocence. "As you wish, Doctor. But if you fall again, I will charge Thorne double for the extraction."

Mara took two rapid steps backward, checking the integrity seal on her right shin. The outer canvas was scuffed and coated in purple slime, but the pressure alarms remained dark. Her suit had held. She looked up at the towering native, her pulse hammering an erratic, undisciplined rhythm against her ribs that she desperately hoped her telemetry logger wasn't uploading to the base mainframes.

"Who authorized you to track me?" she asked, falling back on the rigid, defensive tone of an investigator conducting a hostile audit. "Director Thorne knows my sector coordinates. I did not request a local liaison."

"Thorne did not send me for you," Theran said, turning his back on her with absolute indifference to inspect the rapidly darkening tree trunks. "He sent me to find two geological surveyors who vanished near the southern falls. But their trail went cold—they walked into a sink-leech colony, most likely. Nothing left to salvage but their buckles. On my way back, I felt the forest shouting."

"The forest does not shout," Mara retorted, adjusting her pack straps with aggressive precision. "The flora reacts to biochemical stimuli through standard osmotic and electrical discharge gradients."

Theran cast a slow, pitying look over his shoulder. "If you only hear with your ears, Doctor, it is no wonder you need a machine over your face to breathe. The woods were screaming because an orange beetle was stomping through the nursery of the anemone-trees, breaking ancient roots and leaking dead battery acid into the earth."

He pointed a long, claw-tipped finger toward the canopy. The pearlescent mist was descending rapidly now, rolling down the colossal braided trunks in thick, curling banks that smelled distinctly of bitter almonds and crushed mint.

"We have four minutes before the veil drops," Theran said, his casual demeanor vanishing, replaced by a sharp, focused intensity. "If we stay in this gully, the mist will pool until it reaches your waist. Your filters will choke within ten breaths. Follow me."

"My protocol requires me to establish a defensive bivouac and wait for extraction," Mara insisted, though she watched the descending cloud with rising apprehension. The optical readout on her visor was already beginning to scatter, the laser-rangefinder blinded by the thickening particulate matter.

"Your protocol will preserve a very neat corpse," Theran remarked over his shoulder.

He didn't wait for her agreement. He turned and leaped onto a narrow, upward-sloping buttress of ribbon-wood, moving with the fluid, effortless agility of an animal that spent half its life suspended between heaven and earth. His bare feet gripped the slick, moss-covered bark without slipping an inch, his long tail-braid of black hair whipping behind him as he scaled the rise.

Mara hesitated for half a second. A sharp chime sounded in her right ear: FILTER SATURATION: 14%. AMBIENT HYDROCARBON DENSITY EXCEEDS SAFE FIELD THRESHOLDS.

"Damn it," she muttered under her breath.

She shouldered her pack, gripped her sample rod like a walking staff, and scrambled up the incline after the glowing, amber-skinned guide, leaving the quiet sanctuary of the sinkhole to be swallowed by the toxic twilight.