Ruvle dive-rolled out of the third floor, her useless leg banging and scraping on the iron flooring, her hip twisting in a way she'd pay for tomorrow. The third-floor keycard door slammed shut behind her, and she tossed the card away, panting. Red lights flashed and alarms blared, the robotic defense system now online and scouring the third floor; a spinning blade from a cart-bot had already nicked her paralyzed leg’s thigh, enough blood to stain her black outfit, but not to puddle.

  Ruvle dragged herself halfway up between two blue-liquid pipes, an easy climb even without one leg, before she looked over her shoulder to see a dumbfounded Chain kneeling down, unlocking his briefcase, wild-eyed and shaking his head.

  “Do not go in there,” he said.

  “It’s the safe way out–”

  “Do NOT go in there.” He pulled one end of his scarf out of his briefcase. His eyes were on her useless leg. “Yoris still thinks this is a coincidence, but my cover is paper-thin, we need out and we need out together.”

  “Then keep your cover instead of breaking it with me. Walk out with Yoris,” Ruvle said, and lifted herself up to the nearest duct face. The artificial heart dangled from her neck with string, like a gaudy necklace.

  “No, there’s a huge fucking snake–”

  She climbed inside before he finished explaining. Ruvle wasn’t worried about a single water snake she’d put in there herself; the lab was going on high-alert with killer robots and surely at least three other defenses.

  Chain swore, and she heard banging noises as she scurried through the ducts. The navigation problem presented itself again, this nonsensical maze of air and steel. Scientists and robots ran under some of the grates she passed by; couldn’t drop down there. Risky. She could possibly fight through if she had both legs. First floor. Just had to get back to the first floor, then the front, then–

  Something hissed. Ruvle froze in the middle of a T-intersection. To her right was something so large it barely fit, something with a cybernetic eye and half-cybernetic jaw, its mouth open and fangs stark, slithering closer. Maybe she could punch it. Maybe she could take out its eye. Venom from its seven fangs dripped and destroyed the dust on the vent surface, a chemical hiss more than an animal one.

  She thought better of it and fled.

  A minute later, Ruvle burst out of a vent face and tumbled to the floor, catching with grace on hands and foot, the cyborg serpent close behind. Dead end in the vents, but not the hallway; no other option but to jump out. Scientists in the hallway flinched and backed away in two directions, one of them securing their goggles over their face. Tiny quadcopters flew past the scientists and spun up the circular saws on their undersides, single green lights on their front switching to red. She should have listened.

  Chain hurried to the ruckus, his briefcase swinging and Yoris panting behind him, their feet ringing on the iron. “The intruder!” Yoris shouted, between gasps. A slug fell into his hand and he placed it back on his goggles.

  Tubes shattered and suspended animal parts spilled as Ruvle fought the snake, backing away strategically. One quadcopter in her hand thrashed around as she swung it like a shield, batting away other copters’ sawblades and smashing her own’s rotors. She was doing a precarious job of balancing on one leg, using every decoration of the tubes on the walls as a handhold. The snake reared up on its coils, awaiting an opening. Ruvle’s copter sliced open tubes and the rotting, ammonia-scented liquids added to the chokehold in Chain’s nose. He gagged. Quadcopters with tasers were coming.

  “I’ve got this one,” Chain said, snapping the briefcase open again and unfurling his scarf. “You go get the safety officer!”

  Yoris perked up. “Yes, of course!”

  “Keep everyone away until they get here,” Chain added to the retreating scientist, and once he was out of sight, he held his nose and slung his scarf around his neck. Ruvle, ahead, ducked and bent, getting under two quadcopters and avoiding a lunge from the snake. She rammed her copter against its scales, but the slowing blade of the destroyed bot didn’t even break skin. Its one remaining rotor whirred with gyroscopic stability at the same time that the snake lunged at her again, and she flailed her other arm to grab a tube–with all of that working together, she pulled her waist out of the way just in time.

  “Hey, Dusaw!” Chain said.

  The snake looked up as if recognizing its name, only to be hit in the face by his scarf’s hammer-whip, knocking it back. It rolled and sprawled chaotically down the hallway like casino chips down a staircase, its replacement eye blinking yellow.

  “Go go go,” he said to Ruvle, who was leaning over the broken tube between two intact ones. Panting, she tossed the broken copter. “What’s with your leg?” Chain asked.

  “Normal snake bit me.” She winced, getting onto the tops of two tubes, her ‘good’ leg shaking now, too. “The venom should have…s-stopped spreading by now…”

  “F–we need you out fast; find a window or something,” he said, turning back to the threat. He hadn’t seen windows from outside.

  Ruvle gasped in recognition. “The fume hood in that lecture hall, that way!” She pointed down past the slithering cyborg snake, then climbed fully into the vent. It already had its head lifted and licking the air, measuring him up as food, and he wanted none of it.

  He turned and ran. The second floor looped and winded on Yoris’s map. Chain took a parallel hallway, running between machines that hummed at a higher pitch, dewars of liquid helium towering around him and buzzing, growing frost on their faces. He sped through and took a left, a right, two rights, ducking under two quadcopters. “Which way’s the lecture hall?” he said to a cowering junior scientist, who pointed. And Chain followed. One more right turn, and he found a cracked-open door between tubes. He burst through.

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  Snakes could taste air. Ruvle climbed through ducts. It had followed her here. Ruvle hung a few feet over the door, her hands on the vent’s lip, while the snake Dusaw slithered to find higher ground. Chain shut the door and sized up the area, one hand on his scarf. To his right, four rising rows of chairs. To his left, a chalkboard big enough to write a textbook on, with a tiny desk. Flanking the board on both sides were fume hoods that could contain bunkbeds, with flasks and gripping apparatuses upon the benches, two stools before each. Only the nearest one mattered; the snake slithered up it, onto its sloped roof where it joined with its own special duct, one that rose to the ceiling and beyond. Chemical fumes had to be ejected to outside air. It was their ticket out of here, but also a ladder for the snake to get to Ruvle. It wrapped its back half around three sides, bracing itself, reaching out with the rest of its body, six of seven fangs gleaming in striking distance from Ruvle.

  Chain jumped and hammer-whipped at it–and missed. The snake lunged.

  Ruvle twisted her head at just the right moment, the exact right way, for its jaws to clamp not all the way through to her face, but into the rubber of her full-head mask. The snake yanked away, unsleeving the mask and dropping it to the ground.

  “Get out!” Chain shouted. The gegha swayed easily and glared down with one eye at him, hissing.

  Ruvle, breathing heavily and with her revealed eye drooping, fidgeted with the screws on the vent face. He didn’t have much time. Chain ran under the snake while it dropped down, rolling with meaty thumps down the hood roof and stools, scattering the latter as it slithered. He had to keep distance. Snakes weren’t fast and his scarf had reach; he slung it back behind himself and activated the mirror tislets to make his whips more confusing. Chain raised his henching visor and tossed aside his briefcase.

  The snake reared its head up, judging the distance. Chain’s bicep quivered, ready to strike. Dusaw lunged just as Chain hammer-whipped again, the two strikes glancing off each other, and the snake’s fangs came way too close to his shoulder. He shoved away its head and hustled away while the cyborg coils straightened themselves again. No more risks; a single bite would kill him. Chain fled to the rows of seating and grabbed a plastic-and-metal chair in one arm, hoping to maybe protect himself, a shield. But with distance came the serpent’s disterest, and it turned back, slithering once more towards the fume hood. Ruvle dropped the vent face, cupping something in her other hand. Her wax eye, with its useless vertical slit, held the interest of the very functional one of Dusaw.

  “I said out,” Chain reiterated, running towards it, chair in one arm and scarf in the other. He rammed and whipped into the snake where it hissed back, and Chain crashed into it and lost balance–before he could regain sense of himself, chaos tangled them both. They fell into the tools before the fume hood, and now the splayed legs of three chairs mixed with the fabric of his scarf, the muscle coils of the snake, into a quagmire. Feet of furniture jabbed his thighs and side as he tried to stand, and his head hit the snake’s cyborg middle section. The beast slithered, the chairs sliding apart as it wrapped around, looking for a strike point. Chain pulled on his scarf as he twisted his shoulders, pulling it taut. He thought he could see, past the stool on his right, the fabric get looped around the snake’s body, which it effortlessly slithered through.

  Chain glided a hand along the scarf, grimacing, just barely reaching the active site of the patch of tislets way over there. The symbols lit up, centered on a grid of IKVN, Teeth of the Last Cat, Terminus Varia, and seventy-eight more–and the properties of the fabric changed, gripping like sandpaper.

  He grunted as he stood, fabric tension and sandpaper friction bearing the weight of the animal and furniture, and flung it all to the ground before him. The stools and chair scattered. The snake sprawled and then coiled, glaring at him, but unperturbed. It opened its mouth again, holding still for a split-second to aim its lunge while Chain worked out if he was fast enough to dodge–

  A glint of metal zipped and cracked against Dusaw’s one organic fang, shattering the tip in a spray of enamel. The pained beast twisted its head. Chain took a single glance at where it came from.

  Ruvle transferred one of the remaining three screws in her hand to the other and balanced it on her thumb, her forefinger tense against her thumb knuckle. Frowning with contempt, she stared at the snake with one glazed-over eye. Dusaw shut its bleeding mouth. Ruvle flicked the next screw and it embedded into the snake’s body, drawing more blood.

  Without its horrid venom ready, now was his chance. Chain picked his scarf up off the ground, his hands no longer freely sliding along it–much like he hoped snakeskin would not, just for a second. He dived onto it, this time purposeful, his scarf and his arms scooping Dusaw while it writhed. Its pain-stunning gave him time to pin the snake down and pull his scarf tight, ropes of friction binding it; the snake squirmed below. The third screw zipped and embedded itself through the scarf, into Dusaw’s scales, fastening it to its bindings.

  “Make it…make it still…” Ruvle said, her voice weak.

  With his biceps burning, Chain held the thrashing snake for just a moment longer. Dusaw opened its bleeding mouth in venomous desperation one more time, but Chain planted his foot on its skull, closing its jaw by force. “This still enough?”

  Ruvle bit her lower lip and closed her eye, with what had to be the last of her focus.

  The final screw hit the snake directly in its biological eye, and the fight went out of it in an instant.

  Moments later, Chain caught Ruvle as she fell from the vent, her whole lower body unresponsive–the ever-active flow of that hyperdex simply gone, like so much limp meat and bone fresh from a butchershop. At least she still held onto him tightly with her arms. That was a good sign.

  “...dying…” Ruvle breathed into Chain’s shoulder.

  “You might be okay,” he said, already tying both ends of his scarf around her waist. He tapped the tislets to activate the gauze functionality, the sujecta that he’d deferred into a simpler physia. “It’s not an injection, but it’ll keep you going.”

  “I’m going…” she mumbled rubbing her face against his suit.

  Though not dead, the snake cowered and coiled under the desk, mistaking it for useful cover. Chain hated having harmed an animal so badly, and he would rather leave his mistake alone so as to not see what a cornered gegha could do with the machine half of its face. The last thing Chain did before leaving was collect the evidence–the mask, the briefcase.

  “This way, lass,” he said, carrying her to the fume hood. Climbing inside sucked and required sliding under the workbench’s protective cover, knocking aside glassware and kicking a metal flask-holder onto the floor. But once inside, the vent above had plenty of space for them both, and all he had to do was activate the parachute sequence. He flipped the power switch, air blew, and he held on tightly through their ascent.