Rocky and Grace accidentally found Pandora on the way back to Rocky's planet and now they take vacations to visit Spider.
they go see their little pebble, who (in my reality. ignoring the fact that their two systems are nowhere near each other) saved Grace, by not immediately shooting him in the face, and building him a little fort to hide out in at first, and keeping the others from shooting him in the face, and helping him find food for his trip to Erid.
Grace obviously helps Pandora save their sun, he'll need out with Norm and Max and figure out how to get taumoeba out to their star, and what not. so Spider doesn't have to hide him forever.
but he does at first. when Grace is a random crashed shuttle that barely survived it's fall through a sense patch of forest. he's curious and afraid and has no time to go get other scouts, especially if this is RDA, so he approaches, bow ready.
but he quickly finds Grace and Rocky. and they're clearly no threat. Rocky is... so strange. but he's grown up with blue feline aliens, so... he adjusts quick. and Grace needs a mask, his ship has oxygen, but that's only going to stretch so far. and Rocky is chirping at him while Grace dazedly— the man looks half dead, all skinny and weird colored and... withered —resets his translator.
and Spider decides he'll help them, cause... he doesn't see a reason not to. he helps Grace out of Mary. he's scarily fragile. and him and Rocky have to really manuever him out.
and Spider sets to making him a really nice fort and getting him water and tending his various injuries from his crash landing and the whole starving thing that's made him pretty fragile.
Rocky thinks this human is so amaze amaze amaze. because he's so kind. he's so helpful! so interesting, how he is human like Grace, but nothing like Grace! Grace is so shy about his body and privacy, when Spider— fun fun fun name. like Earth bug —is not. Grace cringes at the thought of being offered "Na'vi clothes" by Spider. it's funny. Spider is so different then all the human things Rocky has learned about Grace. Terran humans and Pandoran humans are so different. Grace lived in an apartment and had a job and technology. Spider lives in a "mauri" whenever he can and has a bow and a knife and hunts and gathers and only uses tech when he has to. tech doesn't "belong on Pandora", he says. interesting interesting interesting. and he wears jewelry like Rocky! and he speaks a different language then Grace and Rocky. and even his English is weird when he does speak Grace's language. nice but weird. kinda like how Rocky's English is weird. and Spider thinks Rocky is sick sick sick, but apparently that's cool!
and Grace... oh he missed kids. he missed kids really bad. he was always better with kids then other adults. and this kid is great. he's so smart, but still loves it learn and is asking Grace surprisingly complex questions about space and astrophage and Rocky and taumoeba. and same with Rocky, asking about Erid and quickly realizing he's the smarter of the two, and teasingly snubbing Grace to ask Rocky questions instead. he's fun and cheeky. and... having missed seeing another human for so long, and then this one shows up, with blonde hair like his, and just... looking sorta like him... maybe his desperation to connect with him makes that bond naturally paternal.
"Grace imprint on similar pebble, Grace cute when he imprints on pebble"
cue Spider tearing up, cause this guy likes him that much? and he's hugging Grace really tight. so tight, maybe forgetting about the whole malnourished thing, that he almost breaks one of his ribs. but Grace just pats his head.
and Spider got him food. good food. better than taumoeba slurries. Grace watches him hunt and gather around the forest and bring it back to him. he's so smart (Grace is literally crying).
and eventually they get his strength back enough that Spider thinks he'll survive meeting the resistance.
and the rest is history. saying goodbye to each other so Rocky can go back to Erid and save his star and see Adrian is hard. there's lots of hugs. and Grace feels like he's losing a child (even if this child is twice his size). and Spider doesn't want him to leave, doesn't want Rocky to leave. but he knows they have to. they leave with new jewelry and a stock of food. Spider has xenonite charms and maybe a blade or something.
but because their systems are TOTALLY neighbors. once Grace is healthy and Erid is safe and Rocky has rekindled his relationship with Adrian enough to take trips, they make trips to come see Spider every few years and totally find a way to pass messages to each other (because I said so)