Love that Rocky gets to exercise his engineer/mechanic muscles to save the mission after all, not just because he gets to build the chain and the taumoeba tanks and sort out the extra fuel for Grace, but because Grace himself (and humans in general) just needs so much maintenance.
Like not only do humans need to sleep and eat much more regularly than Eridians do, but we need like specific conditions to sleep healthily and levels of variety in our diets that Eridians don't need. We need entertainment.
Grace and Rocky aren't doing much Eridian entertainment stuff during their culture sharing montage. Maybe that's because Grace just can't engage with it, given his lack of sonar, but I'm also enjoying the idea that Rocky noticed that the human gets less efficient after working for too many hours straight and needs regular breaks.
Plus the very fact that Rocky wasn't just completely insane by the time he met Grace suggests that Eridians don't need nearly as much social contact as humans do. Like yeah he's traumatised, yeah he's fucked up, but he's still capable of holding a conversation and hasn't carved his own Eridian version of Wilson the Tennis Ball so I think he's doing better than a human would in the same situation.
(Kind of love the idea of Rocky and Grace watching Castaway together at some point and Rocky having the dawning horror of, wait, humans are that emotionally fragile, question? Tom Hanks wasn't even stranded on that island for a decade, what does Grace mean this is normal for humans experiencing isolation, question?)
Very important to me as well that Rocky is approaching this like an engineer.
Rocky and Grace get to Erid and the Eridians are presented with a fuckin' manual that Rocky has been writing while Grace was asleep.
Rocky has timed how long Grace on average can maintain efficiency in a task before he needs to take a break. Rocky has worked out the optimal sleeping conditions for Grace to ensure he sleeps as long and as deeply as possible. Rocky has been keeping track of Grace's heart rate and general vital signs to monitor for anxiety or stress so that he can offer hugs or comfort movie nights at the most efficient times.
This is all completely news to Grace, who just thought that Rocky was very good at predicting when he might feel tired or need a break. Grace wonders if he should feel more annoyed about being treated like a machine that malfunctions when it doesn't get scheduled downtime, except that it's actually working really well.
Plus this means he no longer has to feel guilty about all the scientific experiments he's been conducting on Rocky.