what if Rocky & Adrian in Erid's pre-Astrophage times were DINK Eridians, who were focused on their respective careers and both in agreement that neither of them wanted to raise pebbles of their own?
and then after Rocky sails off into the skies to save Erid and doesn't return, Adrian's family and friends close ranks around them to make sure Adrian doesn't isolate themselves in grief, and one consequence is that Adrian spends a bit more time around their pebble relatives and the pebbles of their friends. and Adrian decides that if Rocky were to miraculously return, Adrian would want to raise pebbles with Rocky if Rocky were open to that.
(But time passes, and passes, and no word of the ship ever makes it back to Erid, and Adrian silently bargains with the universe -- if it would just be merciful and return Rocky to them, they would stay silent on the subject of pebbles until the end of time if that was what Rocky wanted.)
and years later, as Grace and Rocky make their way to Erid aboard the Hail Mary, the two talk and talk and talk about all kinds of things. and Rocky listens to Grace as he recovers and reminisces on all his fond memories of his young human students back on Earth, and Rocky realizes that he himself hasn't actually like. just hung out with pebbles all that much? ever since he was a pebble himself, he was highly dedicated to developing his career as an engineer -- when would he have had the time or opportunity to interact with pebbles, anyway? but Grace makes human kids sound like such amazing little people. Rocky wonders if Eridian pebbles on Erid these days are like that too. and Rocky decides that if Adrian were to miraculously be waiting for him still, Rocky would want to raise pebbles with Adrian if Adrian were open to that.
(But so much time has passed since Rocky left Erid. Rocky knows he's changed, and surely Adrian must have changed -- could they possibly have changed in compatible directions, while so far apart? how much good fortune in the universe could possibly be left for Rocky by now, after he used up so much of it to meet Grace and obtain the solution to save Erid? and Rocky silently bargains with the universe -- he won't press his luck; if Adrian still wants him, that'll be enough, pebbles or no pebbles.)
and the Hail Mary arrives at Erid and things are super crazy and busy for a good while. Rocky and Adrian reunite and move in next door to where Grace's biodome is being built. and sooner or later, the subject of pebbles comes up. Rocky and Adrian are mutually overjoyed to realize that they're actually on the same page about this!
"But how much do the two of us even know about pebbles, really?" Adrian frets, sitting cuddled up to Rocky in the comfortable little niche of Grace's bedroom built especially for watchers.
"We'll be fine," soothes Rocky, tilting his carapace slightly toward the raised platform where a sleeping Grace is just beginning to wake up. "I know a guy."