They see electricity, the same electricity of your brain. If something is not charged they can't see anything at all, and a room of non-conductive objects would be a complete sensory deprecation chamber. They can see a little bit, but they are nearly blind and only use it to notice sudden changes. If you flash a light at them they scream. Instead they just bring a device that generates a charge everywhere they go. They claim their whole planet is charged, but you have doubts

This apparently allows them to see secrets of the universe. They knew about the big bang through out their entire history, because they can apparently just see the beginning of the universe. They find it beautiful, but not all that interesting. You are jealous

Despite being in space, they have not yet discovered steel or had the industrial revolution. It's basically still alchemists and philosophers, but the alchemy and philosophy works and got them to space. You are no longer jealous

They rely on the temperature being way below 40 degrees Fahrenheit so all the fat stays solid and frozen, and die if it's warm. They consider you burning

They get all their energy from air, like eating, to the point they cannot hold their breath at all. They get other things from food, but refuse to prepare it aside from digestion. They just plop it in basically untouched

They age in dog years, dying a few months after turning 9, and only reach adulthood at age 4. That's an absurd amount of time to spend as a child. The one you met is apparently 5 and considers himself a mature adult. The tantrums say otherwise. Yes, he also has arcane knowledge naturally. You are more surprised they live this long considering everything else about them

They have 4 genders and assigned you one, maybe randomly. Kind of rude, apparently very complex, but they have no idea how to explain it. You aren't asking

Closeups:

Rocky and Grace

Okay so these are the 3 portrait sketches i liked the most from my drawing sessions last weekend and inbetween work meetings today :D I find it really difficult to match his likeness on paper. We will see how i can improve on that. Personal favorite is the top left one! The top two references were taken from the Into The Mud Podcast (highly recommended!) and some random interview from the movie premiere (i think?).

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link to the podcast, this section below is from timestamp 24.35

“andy weir provided a packet to the creature shop that was like a packet of eridian biology and stuff but there wasn’t much about eridian culture or eridian sociology and i made a bunch of choices going in because i just needed to have like a ‘who am i?’ right? 

[…] and i made a decision that rocky’s species, that eridians are really social animals that in fact are like a beehive or a pod of dolphins - it’s a unique and really integrated ecosystem of everybody doing their [specific] part. and the fact that rocky had to fly that ship for about 45 years - longer than grace has been alive, i wanna point that out - he’s been alone on that ship, having to run that by himself and- ryan and i would talk about that, one day we sat down and he was like “so what’s the movie from rocky’s perspective?” and i was like “oh it’s like ‘alien’, […] like he’s in a ‘contagion’ movie by himself and he has no idea what’s going on.”

he’s basically in castaway by himself which of course ryan is too but like, one reason why we never cut to the past of rocky is like, i think it was really horrifying! i don’t think rocky has slept in however many years and so a thing i was really struggling with is this idea of like “rocky must watch sleep” because how do you make that a need as opposed to like, a cute idea? and i just had to make the decision that […] he has a lot of unprocessed trauma around the things that he doesn’t understand and how much he is blaming himself because he’s the guy who fixes, he’s the guy who fixes and there was something really freeing about deciding that rocky was a deeply emotional, deeply anxious, deeply horrified person - being - that is trying to move through that in some way and how that affects the early scenes with him until there’s a point in the story where you can see we’ve physically softened rocky’s behaviour, because he’s finally feeling more safe and ok but all of that lore, all of that information [was essential].

James Ortiz read the above, and then he came up with "Rocky watch crew die. Could not fix. Grace say Grace will die. Rocky fix."

you can never get a clear listen to him. his primary sense node is covered in "hair" and the part that isn't is hidden by two crystals that refract sound waves in a pleasing but disorienting way. he covers his body in billowy cloth at all times. not snug and sensible and unobstructive like eridian coverings, but loose and layered, draped and flowing.

the most clear part of him are his internal organs. because yes, the alien's carapace isn't sound-proof. his single heart beats insistingly in his core, his lungs exchanging gas constantly, his long digestive tract always bubbling and contracting. his thorax is packed impossibly tight and it's all moving and singing.

and it shouldn't be possible, with how fragile he is, for that internal pressure to maintain. how does the thin membrane of his external organ (another horror that sends eridians reeling) keep it all contained? his "skin" is so easily pierced, cut, bruised, burnt, how does he not split open under his own mass?

when savior rocky first arrived home and described the environmental needs of his alien, the scientists thought he'd made a mistake in his frantic panic to get everything out. it isn't possible this being lives at such low atmospheric pressure, at half the gravity, and in a gas that's nearly double the weight of ammonia. in a gas so dangerous, so caustic. and if it does then how is it obligately terrestrial like rocky claims? shouldn't it fly or float instead? (and then to see it in the water, learning that it can float or sink at will.)

and this alien has come bearing gifts that will not only save your species but launch it into impossible heights of technological and intellectual advancement. he has discovered the solution to astrophage and bred it to thrive on threeworld and translated his instructions into eridian. he has given your people the complete sum of his people's knowledge, advanced in ways the eridians can't believe and behind in ways that seem ludicrous. and he has given his life for your people to have these things.

he knows how your solar system was formed. he knows how the universe started.

his name means beautiful and generous and relieving.

the eridians experiencing cosmic bliss.

But he also,

Throws fits when things don't go his way. Not a "I'm a bad bitch" destroying everything-type fit, but tossing a trash can, breaking a screen-type fit.

Cries. A lot.

Pleads. He begs.

Doesn't answer the call to action.

Shows weakness. Being a coward and being fearful are two things he defines himself with.

Doesn't end up with the girl. In fact, that girl isn't even interested and he isn't, either.

Cherishes friendship over a romantic plot or something stereotypically brave like, "I'm going to save Rocky so I can save his world." No, he wants to save his friend, first and foremost.

Squeaks. He squeals. He screams, loudly and very high pitched. He whines. He complains. He physically struggles to open a jar. He's clumsy as hell. He makes some of the least graceful noises one can make.

Is not afraid to be the primitive species lowkey.