My fireflies were making me feel guilty. The latest test batch. They weren't flashing. Was their darkness sullen? They roamed their beachball-like enclosure, creepy and cute as always, but were they moving slower? The control fireflies blinked to each other cheerfully in their beach ball. The new batch was ten percent larger than the last, so the growth tweak worked, but why were they so unhappy?
Genevieve burst into the lab without knocking, gorgeous and breathless.  “Nati, come quick. It's Lucky.”
Lucky. No one had any idea how the cat had gotten off of, or on to, a ship from Earth. He had simply been found, in the common room, like a mythic creature born of the mind, orange and insouciant.
Genevieve, as station administrator, took nominal ownership of Lucky. She was also the prettiest woman on the planet. By rather a lot. She had ginger hair and an overbite that gave her a disarmingly goofy grin.
Genevieve also had a husband. The unfairly nice Tim.
I wanted to help her, but I'd added a happy pheromone to trial environment ten and needed to record if the wee bugs cheered up. “I'm in the middle of something?”
“You're our only veterinarian.”
That was an over-statement of my abilities. I was no more qualified to treat a cat than any of the other biologists. I was just less reluctant to. It started with one of the chef's iguanas having trouble laying. Everyone thought it was the higher gravity, but physical assistance (reaching in to grab the egg) wasn’t working. I found the solution in a pet owner’s manual. It was an over-sized egg. I broke the shell and it gushed out, and fourteen normal, intact eggs immediately followed.
From that moment on, I was the vet of Proxima Centauri B.
Resigned to my self-inflicted fate, I followed Genevieve back to the main habitat recreation area. Fireflies, after all, flash from sexual frustration. This was something I knew a lot about.
The main recreation room was cut deep into the living rock. A segmented glass roof let in the soft red twilight that was as bright as days got here, over a ring of halogen lights my research was supposed to replace. Three sickly-looking locust trees grew in specially-cultivated soil pits. Four feet tall so far, the space around and above them depressingly hopeful.
Lucky was laying on his side on one of the couches that ringed the trees. He looked up at our approach and bared his top fangs in annoyance.
Genevieve hovered over him, opening and closing her hands like she wanted to pick him up but was afraid to. “He hasn’t been eating, and he’s barely moved.”
That wasn't like him. He was a troublemaker and an inveterate beggar. I adored him. I held the back of my hand in his eyesight until it was clear he wasn't going to attack, then moved closer to his nose. He let me touch him. “Feels hot. Might be a fever.”
And that was when a firefly came into the room.
He blinked, suspended in the air a few feet in front of me.
I thought I’d imagined it, but Lucky growled, eyes tracking the bug with single-minded feline intensity.
“Is that one of your test subjects?” Genevieve sounded horrified, which made me offended on my firefly's behalf. They weren't radioactive or anything.
He blinked out.
He was gone. I felt sucked into the space he left behind. “I...better check on the lab.”
“Wait!”
Normally, I would never abandon Genevieve, but I'd just witnessed firefly teleportation. Or escape. We don't notice a firefly that isn't alight. 
No, that wasn't better. Either way, there was a breach in my quarantine. What if my populations weren't separate? I'd have to throw out the whole data set and start over! Protocol called for euthanizing the population, giving their bodies over to the soil farm so I could use their habitats with a new batch of eggs. I couldn't bear that. 
I rushed back to the lab and cradled the control group enclosure. Happy, flickering, glossy black bodies. It should hold 227 fireflies bred from the original stock of eggs, minus my ten test groups of ten, and a few casualties. Were they all still there? 
Rather than ask the camera AI to count them, I checked the test groups. Ten bugs easily counted in the first group. Ten in the second, ten in each of them...
The latest test group had only six flies in it. As I watched, another vanished.
I tried to fall dramatically backward into my desk chair and missed. Ow.
Another fly vanished. Only four in there now. Were they all going to disappear? Then one re-appeared. Five. No...four again.
My fireflies…what had the latest retrovirus done to them?
The improved chiton growth virus was old hat, tested. Test group ten also had...I scrolled through the notes. They'd gotten a virus that would tweak their luciferin, make their glow brighter. It should have worked, on paper. Had the pheromone boost done something, reacted with something? No. That made no sense. They were all male, and the scent of female firefly should have just made them...flash a lot. 
Another bug re-appeared, in the lab, outside of the bubble, and lazily alighted on my outstretched finger.
Genevieve leaned in the lab door. “Lucky is making a weird sound.”
I held up the firefly, now crawling in my palm. “I think I’ve made fireflies that teleport.”
Genevieve shook her head. “It's probably a hole in the container.”
“I…yeah.” Whenever anecdotal evidence implies impossibility, test and document. “Maybe I can put trackers on the individuals...I should have marked the population members from the start.”
“Fine. Yes. But work on it tomorrow.”
I stared at Genevieve. “This is important. This...I don’t know what will happen if I don’t act right now.”
“I could say the same about Lucky. He's a citizen of this colony and he could die.”
Genevieve was right. With a sigh, I turned on a camera and pointed it at test group ten. “Okay, let’s take a look at Lucky.”
The cat who had come onto the station without anyone knowing how had contracted a disease no one should have been able to pass to him. Feline Infectious Peritonitis. Untreated, it could kill him. There was a cure, readily available over-the-counter— on Earth.
I got his fever down and got him comfortable with teeny tiny doses of acetaminophen. He wasn’t interested in food. Never a good sign. I set up an ad-hoc cat bed in the lab by folding up two of the oldest, worst lab coats on the bench outside the clean room. One of my lab-mates, Alex, took turns with me petting Lucky and trying to tempt him with eyedroppers of milk from Alex's goat project.
Genevieve came to check almost every four seconds, and after the fourteenth or so time, Alex threw his hands up. “I can't take all the anxiety. I'll go get a head start on priming and stirring the septic tanks.”
Alex never griped about his non-research chores the way the rest of us did, and he had adorable floppy curls. “Is it your turn? I thought you were on windows this week?”
He shook those curls from his deep-set eyes. “I traded that with Jen, so I could trade her KP with Chef, so he'd let me have the milk.”
The most complex structure on all of Proxima B was the chore management sheet.
I'd fall in love with this guy if he weren't gay, and widowed. It wasn't the best way to know someone was single. Still, it had been a year, and my desperation had me trying to come up with a subtle way to ask if he ever dated girls. I almost had it when he saw Genevieve coming in again and beat a hasty retreat.
Genevieve settled on the bench next to Lucky without a word or glance at either of us.
I went back to gluing trackers to ten newly-hatched fireflies. “I sent a message to the relay satellite asking for the medicine.” I shifted uncomfortably, watching Genevieve gently press an ice pack to Lucky's matted fur. She was even prettier with her wispy eyebrows crinkled in worry. “There’s a ship on its way here. It’ll be able to relay the message to Earth when it gets it.”
“That ship is a year away and its message will reach Earth in three years,” Genevieve said, stroking her improbable cat. “And then they’ll take ten to get the medicine here, if they approve it.”
Did she have to say it so bluntly? Sending the message was all I could think to do. “A message could come back faster. They could send synthesizing instructions”...in three years. “Cats...have been known to live a long time. Even sick ones.” 
Genevieve gave me a withering glare.
Yeah. Lucky wasn't going to make it six years, even with constant pets and intravenous fluids, and there was nothing I could do. 
Continuing my work made me feel guilty. Gluing trackers on insects made me feel guilty. The flies squirmed when I let go of them exactly like cats trying to shake a leash. There was a reason I hadn’t become a real vet. I couldn’t bear seeing animals annoyed, much less in pain. It wasn’t exactly a good thing in a biological researcher, either.
I put the tracker-bearing flies into enclosure ten with the three survivors of “the blinks.” When I'd put in tracker-bearing flies from the control group, they had stayed in. There was no opening they could get out of. This experiment introduced new flies who had the same treatments the “blinkers” had.
Genevieve's husband Tim leaned in the door. “Hon? The facilities manager needs you. I tried to hold her off, but she says it's urgent.”
Genevieve looked guiltily at Lucky. His chin was on her hand.
“Go,” I said. “I'll take over. The colony needs you.”
Tim mouthed “thank you” and pressed his palms together, which showed off the beautiful shape of his biceps. All the best people on this colony were married to each other.
There weren't supposed to be any single people.  The project planners thought married pairs would make us all more stable, better able to live so far away from any other human settlement, but my wife and I split not even a year into the mission. We hadn't started research yet, just the toil of getting all the lights working and the heating right and the food crops started. If we'd come to a more finished place, maybe we could have stayed together. But everyone agreed it was for the best. Now she was involved with a woman in astrophysics whose husband didn't mind. Better than having a spouse you still loved, like Alex, and burying him in the first week. Now I felt guilty about crushing on him.
More and more, I was alone with my bugs, the lab rats, the iguanas, the goats. All of them struggling hard to thrive.
I settled into the warmth Genevieve left behind and picked up the eyedropper. “Maybe we shouldn’t have brought any animals with us.” Lucky rolled his head and squinted one eye at me. “Right, no one chose to bring you. Pardon me.”
He let the milk coat his chin and butted my hand away.
I wiped his chin, let him rest, and checked the bug trackers. Two of the test fireflies were now in the larger general population enclosure. With a rush of excitement as strong as sexual frustration, I searched for the others. One was in private quarters half a kilometer away. Another was farther away than the length of our habitat! 
Crap. Genevieve would kill me if she found out I'd broken surface quarantine. We were still hoping to find local life.
The other six were out of range. Out of a two hundred kilometer range. How the heck?
I hated to do it, but I prepared another test group.
I also set a dish of the firefly’s favorite food, heavily scented, into enclosure ten, hoping it would keep them from wanting to leave. Within seconds, two of the missing fireflies returned.
How could that be? How fast and how far were they travelling? It was weird enough they travelled at all. I plotted locations and distances and calculated their speed.
Firefly TG5 was in the test population holding chamber, then he was a kilometer away, the only time delay the speed of the tracker’s radio signal. TG2 had gone over two hundred kilometers and back in...I checked the time stamps. Fifty microseconds? 
I had somehow created faster than light fireflies.
But where could they possibly have gone? They were all healthy, not sickened by the radiation or frozen from space. The only places that far away they could have gone were...the relay satellite and the ship on its way here from Earth.
I looked from my display back to Lucky, his chest rising and falling with labored breath. If only...
There was no way to control them. It would be like throwing messages in bottles into an infinite sea that had no current. I shouldn't even think about it.
I tore open the supply cabinet and counted out all the data chips. I tossed things about until I found a multi-chip writer.
One of my lab-mates came in and dropped the box of specimen slides she was carrying. “What are you doing? You’re using up all the stuff in the lab!”
“If this works, we’ll have a way for people to communicate instantaneously on all human colonies!
And we’d still have a cat.
In the early days of electronic communication, networks lost almost all of their data due to bad physical wires and dropped connections. There was no built-in way to signal back that a message had been received, so data was sent redundantly, in vast swarms, to assure something got through. Like carrier pigeons.
I prepared more firefly eggs with the retrovirus. I prepared chips with a copy of the retrovirus genome and all research related to it, and a request for a particular feline medication or steps for its manufacture. Then I glued the new chips to all my “blinkers.” I watched them start to vanish and immediately regretted it. Where was I sending them? What if those first few were only lucky? Was I killing my babies?
No miraculous response came and my fireflies all vanished. Well, all save one stubborn one I nicknamed “Lazyboy.” He also didn't flash. Not hot to trot, in either sense.
Because once you've wasted material and time the only sensible thing to an irrational human mind is to waste more material and time to make it “worth it,” I used up all the data chips and bred a new population of Blinker Flies. Good work after bad, but they'd come reliably to female firefly scent. Maybe they could remote sense somehow. Maybe that sense would take them to earth.
Maybe I was a terrible lab-mate. Everyone was giving me long, passive-aggressive looks when they went to the supply cabinet.
I used my rest periods to mine for more chip materials. It wasn't like I had a date. 
The remote ore drill was controlled from a cool room with rock walls, near the edge of our underground habitat, with a long, narrow window. It felt like a brutalist mansion's sleeping porch.
The light was good today. Solar flares gave the impression of a progressing dawn. Alex danced in and picked up a pair of field glasses from the ledge under the window.
“Why are you so happy?” I asked. It came out snappish. The ore collector controls were teeny and hard on the eyes.
“Tim is going EVA.” He peered through the field glasses, hips still moving in a dance to music only he could hear.
Alex had a crush on Tim. The sort of crush that transcended the logic that an environment suit would hide any distinguishable hotness.
Alex caught me grinning as he lowered the glasses. He gave a shrug-bow acknowledging his silliness. “Mining for chip silicon?”
“My penance. And we need trace metals. But this vein is dry, dry, dry.”
“Let me try.” I was more than happy to hand over the controls and stand and stretch. It felt good to look out at the rocky surface instead of at a teeny screen full of squidgy symbols. Right outside this window was a gouge in the rock, a feature we called the ice trench. It held slushy water during high solar activity, which made it our best bet for local life. We were all on a rotating watch to go EVA when the water liquified so we could get deeper samples. I saw Tim's helmet poke over the edge as he climbed back.
Alex glanced at me over the controls. “You like guys, too, don't you?”
“Tim's very handsome. If he weren't married to Genevieve, I'd chase him. Well, if Genevieve weren't available.”
Alex tilted his head. “Not disagreeing, but also not why I was asking.” He bit his lip.
Oh. Oh.
I returned my gaze to the view out the window. “Yes, I also like guys. In general. As well as girls.”
“Me too,” Alex said, and winked.
I was afraid to breathe lest I screw this up, but my heart was dancing. If I could find a new lover in a closed community of fifty people who were almost all long-term paired up, well, there was a hope for miracles after all.
Our first date was gluing chips on bugs. 
I came into the lab one morning and found Lucky on the floor by the bench, breathing labored, infrequent breaths. 
Was it the peritonitis or some opportunistic infection? Had I missed a warning sign?
I brought him to the rec center. It was his favorite place. I laid him on what I thought was his favorite spot on the couches. 
I didn't send any messages, but it wasn't a big habitat and people walked through. Alex, Genevieve, and Tim joined me. Others came and lingered. Someone brought a little stuffed mouse they'd sewn together from lint and who knew what. I was crying bad.
“You tried,” Tim said. “Everything you could have done.”
“I just wish she hadn’t killed all those fireflies,” Genevieve said. And winced apologetically. “I...I know you hoped it would help.” As much as she loved Lucky, she was also the boss. 
Alex scowled at Genevieve. “That's it, I'm stealing your man. You don't deserve him.” He was trying to break the mood, but no one laughed. I didn’t say anything. Alex squeezed my shoulder. “It wasn't wasted effort. Don't think that. You could publish a paper.”
I'd run out of firefly eggs. I hadn't met my actual research goals. No super glowy fireflies for our dark planet. It had all been a sort of madness. If they had returned, even now if they returned, there was time to synthesize the vaccine. But they hadn't. Maybe instead of Earth they'd found a planet that was firefly heaven and didn't want to leave. Maybe they were on Earth but no one had noticed their tiny little chip-signals. 
I hadn’t realized how much Lucky’s irascible yowl was a part of my life and I was going to miss it so much. 
Under my hand, I felt him purring through the pain. 
I saw a light flicker. And another. The whispers and shuffling of a dozen people silenced. Lucky raised his head and yowled in annoyance. I looked up, blinking to clear my eyes.
Hundreds, thousands of lights, blinking in and out, danced all through the trees and every surface of the dome. More fireflies than I had sent out, a lot more, smaller, newer, and their number and their size carried a message I didn't have to download from the tiny chips glued to their backs. Someone had gotten my data and reproduced my experiment, made new blinking flies, carrying hope in their light, like a new constellation of stars.