"So what is it?" Doctor Harrington stared through the thick plexiglass viewing panel, still unable to believe the evidence of her eyes as she stared at the... the creature on the other side of the clear plastic window. It looked human--well, humanish--but its skin had broken out in patches of unusual pigmentation that varied from a light, minty green to the deep, rich color of a pine forest. It looked almost translucent in places, as though the discoloration of the epidermis wasn't so much a rash as it was a gradual attenuation of color to reveal the viridian flesh underneath. Its head was flung back, and thick green mist billowed up from its mouth up to the ceiling where a powerful fan carried it away.

"It was a forensic chemist," Agent Rodriguez said, looking at the creature with a sad expression on his lean, rangy features. "We're not sure what happened, some sort of slip-up in lab protocols, maybe... but this is all that's left of them. We've tried communicating with them, but they don't talk. They don't seem to acknowledge our presence anymore. They don't even move as far as we can tell. They just keep blowing out that green crap. We're pretty sure it's uncut X, but it's hard to be sure. You can't analyze the shit, and nobody here wants to try breathing it in. Not when we saw what it did to the other one."

He gestured with long, expressive fingers to the cell next to the chemist. Doctor Harrington squinted, but the room was so full of viridian fog that she couldn't make out any details. Then something shifted, and she realized that there was another of the creatures pressed right up against the glass. It was fully translucent, and its coloration matched the thick mist that filled the small room; only when it moved could she identify it against the camouflage that it had apparently breathed out. Doctor Harrington couldn't help taking a rapid step backward, even though she knew that the plexiglass could withstand assault rifle fire without any significant damage.

She forced herself, consciously, to breathe. "Do you know who they... were?" she asked, once she'd recovered her composure enough to keep her voice from trembling. It wasn't easy; most of her work at this point had been purely theoretical, taking place in a comfortable office with nothing more dangerous to worry about than a paper cut from one of the NASA briefs she studied. She'd never been confronted with an actual specimen, let alone a green gelatinous creature that scratched constantly at the clear plastic walls of its prison in an attempt to break free and infect others with its contamination. Not for the first time in the last twenty-four hours, Joanna Harrington wished her name didn't appear on the top of a very short list of people to call in the event of a highly unlikely emergency.

Agent Rodriguez pursed his thin brown lips and furrowed his brow in uncertainty. "Difficult to be sure," he said. "DNA samples are hopeless at this point--they crash the sequencers, same as the drug crashes lab equipment--and we can't really tell much by looking at them anymore. Our best guess is that the thing on the right used to be Va Thao, from Seattle PD Forensics, and the thing on the left used to be Bryce Penders, a chemist at the university. But it could be the other way around, really. Who knows." His face contorted in horrified disgust. Joanna couldn't blame him.

She tried to cut away the shock and horror, to view this purely as a scientific exercise no different from the hypothetical conversations Joanna engaged in with her colleagues. They came up with them all the time, working out a series of deductions from an initial postulate one of them came up with over drinks. 'What if the aliens used arsenic instead of iron to metabolize oxygen?' 'Was it possible for a lifeform to feed on radiation?' 'Could different life forms perceive time or space differently?' "D-do we know which of them was exposed longer?" she asked, the quiver in her voice betraying her failure. This wasn't a thought experiment. This was two people turned into something outside any human experience, even hers.

Agent Rodriguez shook his head slowly. "They looked pretty similar when we brought them in," he muttered, his eyes a little bit distant. Joanna could guess what he was thinking about--she'd seen the bodycam footage from the officers who were called to the university to respond to the reports of the 'green monsters' who barricaded themselves into the lab and began to fill it with X. It had taken seven men in full hazmat gear to get them into custody, three of which wound up in the hospital from exposure to the gas. The things scrabbled desperately to escape the entire time, constantly trying to make for a nearby sewer grate. It had been awful just to watch, and Agent Rodriguez had been there.

He pulled himself back from wherever his memories had taken him and continued. "The ventilator fans broke in one of the cells a couple of days ago, and the X built up to toxic levels within a few minutes. We didn't dare go in to fix it--once the gas filled the room, the thing started getting active, looking for a way to get out. We think they do the breathing stuff to try to make their local environment more hospitable and accelerate their transformation. The one on the left is still trying to fill up the room enough to change, but the one on the right turned into... that... in custody."

Joanna told herself she should take a closer look. It was right up against the plexiglass, close enough that she could make out the details of the creature's anatomical structure if she got next to it and made a full examination. If she just built up a little courage and took five, maybe six steps, she could make history as the first xenobiologist ever to meet the subject of her field of study. It couldn't break out--it had been trying for days and hadn't even scratched the plastic panel. There were no leaks--she didn't smell any of the telltale odor of mown grass that accompanied exposure to X. She was perfectly safe. Her brain knew that... but her legs weren't buying a word of it.

She forced herself back to first principles. "Do they... have they eaten since being brought in?" she asked. She was certain they must be feeding somehow--the laws of physics didn't change, and certain basics like respiration, nutrition, excretion, et cetera, were impossible for complex life forms to get around. But there were any number of exotic possibilities to fulfill all those requirements, as a sheaf of classified papers authored by one Doctor Joanna Harrington indicated. Finding out what they ate was an important step in discovering what was happening to them.

Agent Rodriguez shook his head. He squinted at the thick mist in the right-hand cell, as if he could see through the glittering mist to something beyond. "No, we haven't fed them. That's probably a violation of some human rights treaty, but...." He shrugged, his voice thick with terror masked behind gallows humor. "They're not human anymore, right? We haven't signed a treaty with Planet Zerg or whatever." He laughed once, a choked gasp of bitter amusement that bordered on a sob. "Jesus fuck. Two months ago I didn't even know your department fucking existed, Doctor Harrington, and now... I'm looking at a goddamn alien. Or at least what it turned someone into."

Joanna didn't bother arguing. Just looking at the thing as it pressed its green fingers against the plastic window evoked a deep, intense revulsion that nothing in her existence had prepared her for. It was worse than seeing those weird fish they pulled up from the bottom of the Marianas Trench, worse than the pictures she'd examined of mutant lizards and bugs recovered from the fringes of Chernobyl. This thing wasn't natural, she knew it with the bone-deep certainty of every human instinct. It was from elsewhere. From outside the experience of her species entirely. For the first time, Joanna truly understood what 'xenophobia' really meant.

And it didn't understand her, either. It moved as though it was unaccustomed to bipedal motion, to even the laws of momentum and force. It didn't hammer on the plexiglass, didn't try to use its gelatinous mass to ram into the window in an attempt to crack or dislodge it. The thing in the cell simply breathed the sparkling green mist in and out, scratched its sludgy fingers over and over against the clear surface as though it was fully capable of outlasting the structural integrity of its prison. As though eventually all matter would yield its way to the creature's patient, determined effort.

Sparkling. Glittering. "Um, Agent Rodriguez?" Joanna asked, hearing the high, quiet tones of hysterical terror infiltrating her voice and utterly unable to stop them. "Are you seeing something... happening to the mist?" Even as she asked the question, Joanna could see the tiny, imperceptible flashes of brilliant white light that danced within the fog of pure X getting brighter, lingering longer, becoming diamond bursts of rainbow coruscation within the deeper green. She could see them through the creature's body, filtered by its translucent flesh but nonetheless visible. Involuntarily, she began to back away from the cell.

Joanna's mind felt like it was simultaneously racing and yet getting absolutely nowhere. She was filled with all sorts of conjectures, suppositions about the nature of the mutagenic drug the things exhaled in seemingly impossible quantities and their effects on a local environment that was, if not hermetically sealed, at the very least insufficiently ventilated to prevent a critical mass from building up. But at the same time, she seemed to take forever to properly process the very basic fact that she'd backed into a solid brick wall and couldn't retreat any further without going left or right, and that incredibly simple decision was utterly beyond her at the moment.

Agent Rodriguez tilted his head, examining the fog with a calm and a patience that Joanna envied. "Yeah," he said, his voice loose and tranquil, "it's like it's, um... pretty, you know? Kind of a pretty color. Kind of a pretty... um." His shoulders slumped, and Joanna realized with a numb, detached anxiety that he wasn't so much tranquil as tranquilized. The lights were pulsing now with a visible stroboscopic effect, growing stronger and stronger by the moment, almost as if they were sending a signal of some sort. And even though she couldn't consciously process it, she understood it nonetheless.

"It's a pattern," Joanna murmured, her earlier panicked tones replaced by a dazed calm. "It's doing something to our minds, h-hypnotizing us. We've got to look away." She didn't take her own advice. She couldn't even blink--if anything, her eyes were widening more and more, her pupils dilating involuntarily to take in more of the mesmerizing flashes that were transmitting information down her optic nerve faster than her narrative brain could understand it. She took a step forward, then another, then another, eating up the space that she'd put between her and the cell just moments ago. It was perfectly safe, she told herself, or at least she told herself that she was telling herself. The thing was trapped. It couldn't break out. It wasn't even moving, apart from its fingers. She was in no real danger.

Agent Rodriguez was moving as well, walking right up to the plexiglass and resting his forehead against it while he watched the sparkling, coruscating lights. Joanna recognized the sheer impossibility of what she was seeing, and her increasingly disengaged intellect began to construct the kind of hypothesis that usually only came up at the very end of several rounds of drinks with her colleagues. 'Alien' was traditionally taken to mean 'from outer space', even in the field of xenobiology, but the entire universe operated according to the same laws of physics. Laws that this thing was blatantly defying. What if it wasn't transforming its local environment to conform to another planet? What if it was creating a zone of congruence with some other kind of space entirely?

The substance couldn't be analyzed. It violated the laws of conservation of matter--the thing in the other cell had been continuously generating X for over two weeks now without food or water, and hadn't lost any mass as a result. Perhaps whatever this mist was, it represented something from outside human understanding. From outside normal existence. Another dimension, a parallel universe, an extrusion of physical laws from a reality beyond the known. And it was replicating here, transforming people... and places? Was that what Joanna was seeing as she pressed her face up against the cool plastic viewing panel, unable to look away?

And when it reached a critical mass, whatever was on the other side could pump a signal through it. They could transmit directly from their universe to this one. That meant the barrier between universes could be broken down with a sufficient density of X in local space. Joanna recognized the implications of her hypothesis, even understood that it was no longer a hypothesis but instead the truth she perceived within the endless sparkling light as it permeated her mind and bubbled up from her unconscious to her captivated thoughts. She understood everything that was happening at last.

It was still a surprise when the other creatures stepped forward out of the mist, though.

Not enough to shake Joanna out of her trance--her breath hitched in startled amazement, and Agent Rodriguez even managed to twitch once before his body settled back down into numb lassitude. But she was nonetheless stunned by what she saw. Something had crossed through that dimensional rift created by the sheer concentration of the X in the cell, a group of creatures that had the same translucent green flesh as the former human but that stood lightly on far too many spindly legs as though gravity was no longer the same inside the plexiglass wall as it was outside. They stared at her, nodded at her, and Joanna could hear them on a level beyond sound. Because the signal was emptying out her mind and preparing her for their control.

She wished she could be frightened. She should be, she knew. The signal was already altering her brain, each pulse flashing directly down her optic nerve and rewiring the synapses that processed language to adapt it to a new and horrifying purpose. If she kept staring, she would begin to mutate that first small and crucial step that allowed her to produce mutagen of her own, and from there she would become another of the X zombies--slowly, perhaps, but inevitably joining the creatures in the cell in exhaling the gas in endless quantities. It should be utterly terrifying. She desperately wanted it to be. But instead, Joanna smiled beatifically and waited for them to escape.

It took less time than she imagined. Their tendrils probed and quested at the plastic, finding the underlying chemical structure of hydrocarbons and altering it in the same way that their offspring had altered its own flesh. The window slowly sagged, turning an emerald green as it absorbed the properties of the X dimension and lost its structural integrity. The original creature had been trying the same thing, perhaps in response to their instruction, but it hadn't yet attuned itself completely enough to the other universe to pull it off. These, though, were natives of the reality beyond. They understood its laws perfectly.

That wasn't enough to save them when the viewing panel finally collapsed, though. As the X rushed out of the small cell, it mingled with the uncontaminated air of the room around it, losing the critical concentration needed to form the bridge to wherever it was they came from. Earth's gravity smacked into them with a vengeance, crushing their glassy bodies onto the floor and squashing them flat within instants. The flashes stopped. Reality returned to normal at last. Joanna felt the signal's grip on her mind vanish....

But then she took a slow, shuddering breath, and inhaled a lungful of pure, uncut X. The creature inside the cell stepped through the gap, wrapping its limber arms around Agent Rodriguez and sealing its lipless mouth against his to exhale directly into him. He slumped to the floor, the thing that was once human falling on top of him, and Joanna realized in the last instants before she sank into a haze of drowsy, mindless euphoria that she was next.

THE END