yeah you get it. that's what fucks rocky up so much about—eridians have a crystalline brain. rocky remembers every single thing that he perceives in perfect detail. he's one of the best engineers erid has ever seen, so it's logical that he double checks his work not just to screen for oversights, but to see if anything new can be added. typically this is done in a thrum, allowing for ideas to bounce off one another.
but rocky was alone at tau ceti for almost 50 years. there was no thrum—not for lack of trying to get his crewmates to respond—so rocky does it himself.
so rocky gets stuck in loops. his brain rereads the same information over and over again, expecting to be passed onto another one of his species. when it isn't, there's no sense of completion and the loop starts back over. not having another eridian translates to stress on an instinctual level so his brain thinks there's an error in the loop or in his work. he completes a ritual or task to satisfy the anxiety. the cycle repeats itself regardless because eridians are not meant to be alone.
he has to check on grace's breathing. he needs to check the taumoeba. he needs to make sure he isn't dying of radiation sickness. he needs to force feed his friend as he wastes away. there's so much rocky can't fix and so much that he could have if his crew was still alive (if he didn't kill them). it starts to become more irrational—tapping in sets of five on the xenonite barrier to make sure it's stable. saying words over and over that don't really make sense with eridiani sentence structure. if he doesn't click and shake his carapace, his brain will make him relive the fat of grace's arm liquefying and coagulating in his hold.
inside his body, his worker cells are exhausted from constantly going to repair a sickness that doesn't exist. his cells are the sickness, driving themselves to ruin in a never-ending death spiral.
he's so, so tired, but he can't go to sleep because he has to check.