Archive of Our Own

Rocky knocked three times against the wall.

It wasn’t his smartest decision. Knocking three times was only customary in Eridian culture. The alien, or Solarian to be precise, wouldn’t have known that. Rocky still hoped that the sound would attract their attention. His waving to the Solarian seemed to have gone ignored, much to his dismay.

Rocky barely believed his carapace when the Petrovascope found the other ship. When the detector first blared out a warning about a truncated Petrova line, Rocky had to resist the urge to punch it. With the thermostat, spectrometer, and essentially half of the ship requiring constant repairs by now, fixing the Petrovascope too was nothing short of irritating. But as the days passed and the beam coasted and intensified, Rocky kept finding no malfunctions. 

Somehow, against all odds, there was another Astrophage powered ship.

The Solarian was massive, far more so than its meager ship suggested. They sounded imposing across all of the many textures he’d offered them. They towered above his own height, and above twice the height of any Eridian. They remained perched on their two hind arms, but even in their normal stance they would stand well above his height.

At least, if he assumed that all of their limbs were supposed to touch the ground. But as the seconds passed and the Solarian remained perched on their hind arms, Rocky grew less sure of his theory. If only an actual biologist was here.

Of course, the thought of another Eridian led to thoughts of sleeping as another Eridian watched or thrumming again, which had long since faded from depressing into numbness, so Rocky cut himself off by focusing on the Solarian even more.

Despite the Solarian’s sheer height, its ship was anything but large. The Petrovascope found the magnitude of the Astrophage trail, but hearing it in person was another matter entirely. It was far too small, like seeing one Eridian carry a house on their back. Rocky had seen stranger physics though, especially when travelling to Tau. Imagining that a species could fly that efficiently, while unimaginable to the rest of Erid, now seemed more than possible.

The Solarian knocked against the wall thrice, well above Rocky’s height. They paused for a moment before they pointed one of their fingers back toward their ship. They left as quickly as they came.

Rocky bounced briefly between his legs, thankful the Solarian finally responded. Rocky guessed that the Solarian would try to analyze the wall’s alloys, and he quietly hoped that they would pick a favorite. Or alternatively, they would stay away long enough for him to work.

The Solarian returned with a few key items. They scattered a few devices across their side of the airlock before pointing some sort of instrument at the wall. It might have been some sort of spectrometer, but Rocky knew better than to speculate confidently on alien technology.

He’d waited in anticipation until the Solarian finally moved. It awkwardly paced back and forth for a few moments, before it suddenly turned to its right.

“ Holy cow! ”

Rocky knew the Solarian’s words would be different, but he was still surprised. They only made three notes, but they were a far cry from Eridani chords. The volume and pitch wavered like the wind, and the sound almost felt like a sentence concentrated into a single word.

It was, without a doubt, alien.

The Solarian took to one particular hex in particular, one more suited to lower atmospheric pressures. It seemed as though their atmosphere was weaker than Erid’s. He’d figure it out, of course, once the Solarian gave him room to work.

Rocky moved a hand toward the hex. In response, the Solarian pressed their whole body against the wall for just a second, until they pushed back. They probably wanted to know what Rocky looked like, and were using the best hex for their environment as their window.

Once again, Rocky tapped the hex. The Solarian followed suit.

Then slowly, he raised up a model of the Solarian. Or more precisely, the robotic Solarian they had. Rocky had yet to find it, but as per Eridian technology, the robot resembled the Solarian itself enough. Then after raising a model of the other ship, he pushed the model Solarian into its airlock.

The Solarian gave an odd gesture, extending one of its fingers upwards. Rocky emulated the gesture, hoping that it was a Solarian sign of approval.

He was right. The Solarian slowly backed off into their ship, closing their airlock behind them.

Rocky would have been bouncing around in sheer joy if he wasn’t suddenly busy. He told the Solarian to stay put, so it was only fair that he worked quickly. First and foremost, he needed to sample the Solarian’s air. It would help with determining how sound waves traveled through their atmosphere, but Rocky also hoped that their environments were similar enough to merge atmospheres. Atmosphere composition probably wouldn’t be a problem for him, but temperature and pressure would be.

He rushed a few probes over to the Xenonite wall, poking each of them into a hole he’d made earlier. Then, by firmly shoved each probe into the atmosphere beyond, he could scan the Solarian’s atmosphere. His radiator shivered in anticipation as he hustled to finish working with the probes.

The probes unceremoniously made their first beep of approval, before they began repeating each of their measurements in their usual, monotone voices.

293 Kelvin. 0.4 Atmospheres. Only oxygen.

Rocky paused for a moment, his whole body slumping.

His immediate thought was denial. Those measurements couldn’t have been right. Rocky even bluntly kicked the spectrometer again, half inclined to believe that it was broken yet again.

It wasn’t broken. Rocky knew that. He’d tested the probes on various atmospheres and temperatures to prepare for the Solarian, and molecular gases were some of the easiest to detect. His mind also supplied that as toxic as the other side of the wall was, liquid water could exist there. Technically, life could live in those environments.

If only it wasn’t the most toxic environment possible.

Rocky let out an unprofessional whirr, hoping that the Solarian couldn’t hear him. Even the boldest of Eridian xenobiologists would have struggled to imagine an environment as hellish as that. There were temperatures 200 Kelvin lower than Erid. The pressure was almost vacuum, at around 1/73rd the pressure of Erid. But the worst part was easily the oxygen, one of the most electronegative gases to grace the cosmos. Any Eridian would die in a matter of seconds as they writhed in absolute agony.

The pure oxygen was odd. Never mind how a species could breathe oxygen, Rocky wondered how a planet would develop a pure oxygen atmosphere in the first place. It seemed oddly coincidental. Perhaps the Solarians used lower pressures on their ship. But even when Rocky made that assumption, going so far as to base a Solarian biology on some Erid cells, 1/29th of the atmosphere was still shockingly low.

Then again, the rest wasn’t much better. Their living temperature was even colder than Astrophage’s enrichment temperature.

Their living temperature couldn’t enrich Astrophage.

Rocky turned back into the temperature probe, and sure enough its measurement was the same: 293 Kelvin. A far cry from Astrophage’s 370 Kelvin. With a planet so cold, Solarians would have to make their own Astrophage.

Suddenly, their ship design made far more sense.

Rocky firmly gripped the ground with all five of his hands. Solarians had to manually make their Astrophage; they couldn’t use their oceans. The ship was small because they couldn’t make any more. They limited their atmosphere due to the draconian mass restrictions. They only sent one Solarian because that was the most they could send.

Rocky shuddered. Even after sleeping along for years, imagining the Solarian willingly going alone, never mind sleeping alone, was terrifying.

Rocky hissed, focusing again. Their environments were not compatible, but they had a backup plan. Really, it was closer to the main plan. The Solarian had chosen a wall material, one they liked to react through. The next step was to remake the wall with that material to improve their communication. So with thoughts of sharing atmosphere casually thrown aside, Rocky marched over to the Xenonite liquids. It was time to build.

Rocky waved at the Solarian from the other side of the wall.

Even that gesture made him feel awkward. It had been years since he’d thrummed, years since he'd talked to another Eridian, and now he had to communicate with a literal alien. He only had one greeting, and he hoped that the Solarian would give him more to work with.

The Solarian shook the oddly bulbous appendage on top of their torso.

Yet another odd quirk of Solarian biology. Instead of having one major body cavity, Solarians had two: their main body and a bulbous appendage that stuck out of their torso. It wasn’t an arm, not without any fingers, so it appeared to be an extension of their main body. The odd bumps and creases that graced most of their upper appendage looked unsettling, but he presumed they were normal to Solarians.

In response, Rocky shook his whole body. He definitely didn’t have the anatomy to copy the Solarian perfectly, but that was close enough. But as intriguing as Solarian biology was, they had business. Rocky tapped firmly against the wall, pointing at the spheres he left the Solarian.

“ All right. Let’s see what you left me, ” the Solarian muttered.

“Open the spheres,” Rocky hummed, hoping that the Solarian might somehow understand.

Instead, the Solarian flinched, opening a whole cavity in its upper appendage. Rocky almost didn’t notice, but the Solarian appeared to talk by opening and closing that cavity. It was disturbing. Almost like they were constantly trying to eat the air in front of them.

“ You have a language! ” the Solarian protested. “ How do you have a language!? You don’t have a mouth! ”

Rocky silently thanked that for once, the Solarian bothered to repeat a work. Language . Perhaps it was the Solarian word for life. Or for Eridani.

“Focus,” Rocky hummed back. “Spheres.” As interested as he was in the Solarian language, that could wait. The Solarian needed to know about his environment.

Despite not understanding him, the Solarian complied. They floated over to the spheres he left and managed to open both. Once opened, the atomic models for oxygen and ammonia they contained float around aimlessly.

It was a primitive method, but an effective one. No matter how different Solarian science was, elements and molecules existed everywhere in the universe. A species that made it to another star most certainly discovered the charge of oxygen and the structure of ammonia. Rocky worried that the sheer number of ammonia atoms he’d needed to represent his own ship’s atmosphere would confuse the Solarian, but there was no alternative to representing pressure.

“ This reminds me of something... ” the Solarian said as it pressed a finger to their upper appendage. “ What does this remind me of… ?”

Rocky copied the Solarian’s gesture by raising a finger to his carapace. He also noted yet another repeated Solarian expression, perhaps for thinking.

“ Molecules! ” the Solarian suddenly stated, holding out “ These are molecules! You’re trying to tell me something about chemistry! ”

“Come on, just figure out I breathe ammonia,” Rocky whirred. He realized that he wouldn’t be able to tell if the Solarian figured out his atmosphere, but he could hope.

“ Atoms! ” The Solarian decided to chime out with yet another word. Perhaps it was theorizing to him. “ The beads are protons . So the circles of beads are atoms. And the little connectors are chemical bonds! Okay, if that’s the case... ”

Suddenly, the Solarian thrusted out the model oxygen atom. “ You clever fellow, this is my atmosphere! ” They followed by thrusting out an ammonia atom as well. “ So your atmosphere is… seven protons connected to three individual atoms with one proton each. A nitrogen attached to three hydrogens. Ammonia! Of course it’s ammonia! You breathe ammonia! ”

Rocky slowly lowered his carapace in relief. While he couldn’t understand the words, the Solarian seemed to understand his model. Admittedly, it wasn’t perfect. His assumption that the Solarian brought a different component atmosphere than they normally had, never mind his approximation for Solarians with Erid cells, had many flaws, but also pieces of evidence too. The most glaring piece was that one way or another, the other ship was severely mass-constricted. Still, seventy atmospheres or twenty-nine atmospheres, it would be obvious that they had completely different living environments.

“ Yikes. You breathe ammonia? ”

The Solarian repeated yet another word. Rocky was inclined to believe that the last word may be Solarian for ammonia, or at least related to atmospheres.

The Solarian’s upper opening also appeared to change. While its ends were originally pointing up, now the opening was more or less flat. Rocky couldn’t even begin to fathom that change.

Before Rocky could think once more, the Solarian held up a finger, which he matched. They then rushed back into their own ship before bringing back two objects.

The first was some sort of disk, with faint sticks Rocky could barely hear. It takes until the Solarian spins the hands for him to make the realization: it’s a Solarian clock.

The Solarian followed up on this revelation by moving the clock sticks around before pantomiming each stick at a new angle with a pointer. It seemed as though they wanted to leave for a while.

In theory, the set-up was fine. In practice, not so much.

Just looking at the clock almost hurt. Each hand was so thin that it was practically invisible. While Rocky would remember the angles, hearing the hands was a different story. The three different mediums in between the clock and him didn’t help.

“Pull it forward,” Rock hummed. To try to explain, Rocky pulled the empty air in from of himself toward his body

The Solarian seemed oddly very confused about the thought. As if it wasn’t obvious. Solarian hearing must have been very precise. Their thin atmosphere might have encouraged more sensitive hearing, hence why their clock sticks were so thin. Nevertheless, after enough frantic gesturing, the Solarian finally pressed the clock against the wall and taped it there.

For one final act, Rocky tapped firmly to keep the Solarian’s attention.

“ Dude, I just want a darn nap! ” they growled. Rocky wasn’t sure what they meant, but he took it as a sign to hurry up.

Rushing back into his ship, he came back with his own clock. Unlike the Solarian clock, which relied on angles to tell the time, the Eridian clock displayed the base 6 number system they used. Rocky still preferred Eridian clocks, mostly because they had numbers instead of angles.

“ It’s a clock! I showed you a clock, so you showed me a clock! ” the Solarian chimed. Already, Rocky was starting to see a few patterns in Solarian language. ‘ I ’ and ‘ you ’ came up a lot, so they were Solarian for a common word. He also had a decent assumption for ‘clock’ and ‘ammonia’.

“ I like you Rocky! You’re a genius! ”

Once again, the Solarian reused ‘ I ’ and ‘ you ’. His theory seemed to be firm.

Shortly thereafter, the Solarian hustled around, bringing over a few instruments. Rocky wasn’t completely sure, but they seemed to be time measuring instruments. Rocky couldn’t see any numbers on any of their instruments, so he could only wonder what exactly the Solarian was doing.

Eventually, the Solarian abruptly ended their work by circling a point on their clock and shambling away.

Rocky tilted his own carapace, wondering why the Solarian left. He waited for a few minutes, but the Solarian refused to return. In response, Rocky stamped the floor three times, trying to find where the Solarian was. He eventually heard an extra lump that was about as large as the Solarian lying somewhere, motionless.

They were sleeping.

Rocky felt a pang of guilt wash through him. He kept the Solarian up for a while, perhaps too long. Their body was probably overheating; he knew he wouldn’t have left a moment as consequential as first contact unless it was to sleep or eat. The time they gave was an estimate for their sleep schedule.

Rocky tuned into the clock again. The short stick had barely moved, and the long stick hadn’t moved much either. The Solarian would need a while to rest.

Letting a breath rush out of him, Rocky turned his attention back to the wall.

It wasn’t his first choice for a wall, but he respected the Solarian’s decision. Hearing the other side was a struggle with how different the mediums were, but he imagined that the Solarian enjoyed how it made hearing on their end easier.

Of course, it was still just a wall; there was no way to give the Solarian more items. At least, not without taking another hour to remove the wall again. Rocky wished that there was some sort of airlock he could use to give the Solarian items, only to remember he was one who designed and built the wall.

Rocky let out an irritated breath once he put the pieces together. If only he thought to build the airlock into the current wall.

Rocky turned his attention away, listening to the Solarian once again. They seemed to be sleeping well.

“You can sleep, I can watch.”

It was a millennium old oath that every Eridian knew, but easily the most important one. Even if the Solarian couldn’t hear or understand him, saying it again was a breath of fresh air. The Solarian was counting on him to watch them; he was responsible now. He wouldn't let the Solarian down.

Rocky briefly wondered if the time was important enough for repeating the age-old phrase. It was only ever repeated for the most important events. But given the circumstances, there was only one answer.

“You can sleep, I can watch.”