"Do you hear that, my darlings?" Tana's eyes widened, and she glanced up at the underside of the habitat dome as if she expected to spot something moving overhead. The others looked up as well, but the only thing they could see beyond the transparisteel hull was swirling snow. "I think that we may be getting a little visitor tonight! A very special visitor, with very special gifts for each and every good little colonist on the anniversary of the most important day in the history of Corvus-9. And do you know what that is?" She smiled beatifically at them, encouraging them silently to make a guess.

None of them answered. There were five girls and three boys this year, and they all simply glared at Tana with the sullen defiance so common to those not yet adults, yet no longer children. Even Jarl, the oldest, who had turned eighteen almost a full year ago, merely stared at her in stony silence. Tana didn't really expect them to behave any differently. She had been much the same on the night when she was gathered with all of the other colonists her age for the special ritual that marked her transition from girl to woman. They would all understand soon. Just like she did.

"Tonight, my darlings, is Parasite Eve. It's the last night before you take your place in the colony as fully recognized adults, with all the privileges and responsibilities that entails." Despite herself, Tana somehow expected them to react to the news--with excitement, shock, dismay, even perhaps fear--but their faces betrayed only hostility and confusion. More confusion than hostility in the case of Jarl, it seemed; he'd been asking when he could move out of his parents' dome and begin building his own habitat, and the answers he'd gotten hadn't satisfied him. He was no doubt curious to discover why so many friends who were older than him by a mere week or two were already treated as fully grown, while he was still relegated to the curious in-between status of the other eighteen-year-olds in the colony.

But that was only to be expected. Parasite Eve was one of those rare and wonderful traditions that didn't come with them from the homeworld; unlike the tales and stories they passed along to their children, none of their written histories recorded the legendary night and the even more wonderful and glorious day that followed. It was down to Tana to tell them how it all happened, a duty that she welcomed every year. "Let me tell you," she said, "of the very first Parasite Day. And the very special visitor we can expect quite soon."

She gestured up to the transparent surface of the dome overhead. "It was on a night very much like this one," she declaimed, her voice settling into the rhythms of the story she knew so well, "in the very first year of the founding of Corvus-9. The original settlers had only a handful of domes back then, and the world outside them was even darker and colder than it is now. They knew that the work of turning this planet into a place where their descendants could live without environmental suits and habitat technology was long, dangerous centuries away, but they lived in hope. Just as we live in hope that our children's children's children will someday stand on the surface and look up at a bright blue sky."

Tana assumed that at least that would bring a smile to the young colonists' faces, but all they did was sit in disdainful silence, broken only by the occasional sound of Nari's squirming and wriggling or Cheema's quiet sobs. The in-betweens never truly understood, of course; that was what made Parasite Eve such a special night. But this bunch was particularly obstinate in their disrespect for the colony's traditions. It was probably Jarl, she suspected. He'd grown nosy and suspicious over the last few months, and he'd no doubt bred suspicion in the others as well.

They'd understand soon, though. "But even in that first year, the founding settlers had expanded their reach from the original Central Dome to a second habitat, then a third, and so on until on the first Parasite Eve they finally christened Dome Seven. This very dome we sit in tonight. Oh, I know that now it's just part of the wide and sprawling complex we live in, but back on that long ago evening when the snows blew hard and the skies were black as carbon it was the furthest a human being could go in the entire world. And twenty families shared this little space that feels cramped for just the nine of us!"

Tana exaggerated slightly--the eight in-betweens were all packed a little closely, yes, but that was just to make the ritual easier when the time came. There was plenty of space for a single family, not that any family lived in Dome Seven. Officially, this habitat was earmarked for storage and social gathering, and evacuated every evening promptly at Red Ring. People only stayed overnight in it once a year... but that was what made it such a special event.

"And those first twenty families were all so young," she continued, trying her best to paint a picture with her words despite her unenthusiastic audience. "There were no children on Corvus-9 in those days; pregnancies wouldn't be authorized for another three years, in fact. It was only fertile couples, working hard to make their environment big enough and safe enough to support the little ones who would someday arrive. And so those forty individuals, the twenty families who lived here on Parasite Eve, were the first to hear their new neighbors knock... knock... knocking on the dome."

That finally got a reaction. Cort looked around wildly, as if he expected at any moment to see something on the other side of the transparisteel walls. Nari squirmed so hard that her chair tipped over, sending the breath out of her with a whoosh. And Jarl... their little ringleader Jarl... he looked at Tana with a glare of triumph and fury mingled together as if he expected her to say something just like that. It was a lucky thing Parasite Eve was tonight, she decided. If his suspicions were that fully formed, who knew what he might have done in a few more days?

She decided to leave Nari lying there for a little while. It might teach her a valuable lesson about struggling too much. "Now, I'm sure you all remember from your lessons as children that Corvus-9 is uninhabited. There's no life anywhere on the planet, right?" Muuna let out an angry, muffled grunt in response, which Tana chose to interpret as agreement. "Exactly. We teach you that because that's what the founding settlers thought, back in the days when the first domes were being laid down by the drone surveyors and this whole colony was just a dream in the making. And just like those first settlers, you'd probably be very frightened if you heard someone knocking from outside."

'Frightened' probably didn't begin to describe it. They would have known there was no chance that it might have been a prank of some sort; even if terraforming was an endeavor that tolerated people given to jest, instead of those focused on the razor-thin margins of survival in a first-generation colony, going outside on the coldest night of the year back then was simply unthinkable. Three hundred years of environmental engineering had made it merely incredibly dangerous to be outside in the -95C chill; back in that first year, it would have been twice that frigid. Even with a suit on, any would-be practical joker could have measured their lifespan in minutes outside of a dome.

"Some of them no doubt thought it was their imaginations at work. Others perhaps imagined some natural phenomenon, a windstorm combined with larger-than-usual snow crystals. But then they heard it again. A knock... knock... knocking on the metal surface." This time, all eight of the in-betweens glanced around, their eyes wide with terrified expectation. "The sound of something the surveyor drones missed. The sound of a visitor from the planet they called home."

Nari's struggles became contagious, with Muuna and Rinc both straining against the ropes that bound them to their chairs in a desperate effort at escape. Tana only smiled at them indulgently, remembering her own attempts to break free back when she was eighteen. It seemed so long ago now, even though she was barely even thirty; then again, life before Parasite Day always did.

She watched, still smiling, as their efforts to loosen their bonds ended with them sagging back into their seats in quiet despair--the duraplast ropes were designed to handle much heavier stresses than a recalcitrant in-between could bring to bear. None of them were going anywhere tonight. They were going to hear the rest of the story, and then they'd understand why it had to be this way. "Those twenty families heard their neighbor before they saw it," she said. "But they saw it soon enough."

Koli screamed, then, but thankfully it was muffled by the gag in her mouth and didn't distract the others overmuch. "We know now that the surveyor drones missed it because it was a very different kind of life than anything we were used to. It lived in the ice and snow that would have killed a human being, and the coldest of nights were when it became strongest and boldest. It watched us from afar at first, as we went out in our survival suits and built our habitats... and on the very first Parasite Eve, all those hundreds of years ago, on the very darkest night of the year, it became bold enough to come and see us at last. It pressed its body against the insulated surface of the dome, and the colonists screamed because they didn't understand what they saw."

Speaking of screaming, Koli was no doubt going to make herself hoarse carrying on like that. Why couldn't she be more like Jarl, who'd spent this whole time glaring at her in stoic silence? Even Cheema's sobbing was tolerable by comparison. Honestly, anyone would think that her parents had genuinely injured her when they subdued the poor confused girl. Tana sighed, forcing herself to speak up over the din.

"The knocking continued for almost three hours," she said. "It dented the dome there... and there... and there." Tana pointed to a few spots where the transparisteel was pocked with almost insignificant marks, marks that every adult in the colony knew by heart. "And they trembled with fear, and some of them even thought of fleeing for their lives despite the danger of using the tunnels on a night colder than any they'd ever experienced. But they huddled together, instead, waiting for an end to the long darkness. Waiting to share the news with the others that they were not alone. But before morning came... the First Parasite entered the dome."

Tana paused for dramatic effect, but Jarl quite spoiled the moment by slicing through his ropes with a plasma knife that he must have concealed inside his sleeve. It appeared he was even more suspicious than they thought, if he'd made plans to escape in the event of his capture. One of the parents probably got sloppy in their preparations, made it just a little too obvious that Parasite Eve was coming and the in-betweens were to be induced to come to the festivities by any means necessary. Honestly, it was so frustrating to find out that someone nearly ruined everything by wrecking the wonderful surprise like that.

Still, Tana knew how to handle a party pooper. She lunged to her feet, easily evading Jarl's clumsy slash, and pressed her lips to the side of his neck. A growl of satisfaction emerged from her throat as she felt the needle unsheathe itself from the hidden pouch in her tongue, and Tana felt a surge of visceral, almost sensual pleasure as she jabbed it into Jarl's flesh. He continued to struggle for a moment, but she kept pumping her hypnotic drug into his veins until his plasma knife clattered to the floor and she went limp.

"I'm sorry," she said, letting go of the unconscious boy and returning to her seat. "I didn't want any of you to have to see that. Now there's only going to be seven of you that hears the full story." The other in-betweens stared at her, eyes wide with fear, and Tana realized that they must still be able to see the thorny protrusion at the end of her tongue. "I promise, darlings, I will explain everything. If only you're patient and good."

They remained frozen in petrified terror, which was close enough for Tana's purposes, and she continued. "The First Parasite was just as frightened as the colonists when it first entered the dome. The tunnel was strained to the limit of its environmental controls, and when the native Corvoid breached its way inside the systems soon gave out and allowed it to stay nice and chilly and comfortable... but once it came through the emergency airlock, it felt a terrible heat all over its body that was just as painful as the cold would have been to the colonists. That was the true tragedy of Corvus-9, you see, even though nobody knew it at the time. The same terraforming process that will someday make the world safe for us would have ended the Corvoids' whole species."

Tana forced the spike back into its sheath to make her speech a little easier. "But the First Parasite was the strongest of its whole species, strong enough to survive even the heat inside the dome for a little while. It slithered its way to the closest colonist, and found that just the tiniest little pinprick of the special, sleepy drug it carried in its stinger was enough to numb the human's mind and make them all docile and tame. That's the very same drug that I used on Jarl, although he got a bigger dose. Because he was more trouble." They didn't need to know that her venom sac was almost entirely empty now. Let them think that she could do the same to all of them, if it kept them quiet just a little bit longer. 

"And then the First Parasite extended a tendril inside the colonist's mouth, sensing somehow that despite the intolerable heat there was something within them that cried out for investigation. And that, my darlings, was when the miracle of Parasite Eve happened. The miracle that saved us all from the guilt of genocide, and made Corvus-9 a wonderful paradise of peace and harmony for all of us. The miracle that we celebrate tonight, and every Parasite Eve for over three hundred years.

"Somehow, despite the yawning gulf of very different biologies that separate us from the Parasites, that tendril was able to exchange genetic information with the human that was soon to become the very first host. It transformed the human's body into a biological environment that could support it, and the human transformed the First Parasite into a creature that could live inside of them. Much of that alien body sloughed away, doomed to perish in the heat of the dome, but the core of the creature, the vital centers of the native Corvoid, survived inside its new home. And it touched the mind of the person it had joined with, and helped them to understand who they were and what they needed to do from now on."

Tears streamed freely down Tana's cheeks as she imagined that first communion. It must have been very different from her own; she'd been told what to expect, even if her anticipation was no doubt clouded by fear and mistrust when the parasite entered her. But that first colonist would have had no idea what was even happening to them. They would have felt their thoughts smoothing into the warm, peaceful harmony of surrender and not even known where their sudden urges came from. Even with the drug taming their will, it had to have been the most amazing leap of faith to give in to that calm, alien intellect and submit to its loving control.

And that would have been as nothing to the shock they must have felt at what happened next. "Once they understood one another, the First Parasite fissioned inside its host, creating a second. The colonist stood up, went over to their partner, and kissed them... and in that special, wonderful kiss, the second host was made. One became two, then two became four. Then four became eight, and soon the whole dome knew the rapture of communion with the parasites. And they passed the night, sharing the gift of surrender with one another, until the sun rose again."

Tana's head fell back on her shoulders in bliss. "That was Parasite Day. The most magical day in the history of our whole colony. The new hosts repaired the tunnel and spread out from dome to dome to dome, sharing the gospel of surrender to our alien masters with kiss after magical kiss, finding each and every last colonist and showing them a whole new world of beauty within the sweet, tender embrace of the parasites' all-powerful will. Oh, there was fear at first. Just like the colonists were frightened in the night, just like you're frightened right now. But everyone who was touched by the rapture of communion soon understood that it was the best way. The only way."

Tana shuddered, her tongue flicking uncontrollably for a moment as the parasite within her fissioned in two. "And now, darlings, it's time to share that gift with you. Your bodies are finally mature, ready to handle the changes that come with being a host, and tonight is Parasite Eve. And soon, you will be one of us at last." Her speech slurred, the sudden doubling of the guest in her mouth making it difficult to talk and causing drool to run down her chin as she struggled to make herself understood. She stood up, her gait lurching just a tiny bit as the twin aliens sent simultaneous and overlapping commands to her muscles, and headed toward the in-betweens. Jarl had ruined his chances to be first with his petulance--she'd overreacted a little, drugged him so deeply that he'd sleep until morning. He would have to go last instead. But the process wouldn't take long, not once Tana had a nice little helper for her labors.

She stood over Nari, still lying on her back and struggling to free herself. Yes. The girl had spirit, and she'd soon turn that same energy to aiding Tana in the night's festivities. It was just a matter of showing her how. "That's it, darling," she murmured, as she removed the in-between's gag and the woman-to-be opened her mouth wide to scream. "Just like that for me now." She straddled Nari's chest and leaned in for a kiss, and once again the miracle of Parasite Eve visited the dome.

THE END