For me the gracerocky appeal is about how suffocatingly intimate everything about them is. Like, the level of vulnerability and trust they have to have with each other after taking the time to literally study each other inside and out. At that point something like sex is so far from feeling like a huge leap to make. They're each other's entire universe during those years on the Hail Mary, of course they would both be interested in what makes the other feel pleasure (and deriving pleasure from it themselves). Who cares about the barrier between them, they want to melt into each other's bodies and live there. They're practically a single organism by the time they reach Erid due to the forced proximity (although I doubt either of them would ever think of it as "forced").
For Grace specifically, I like to think that sex was always something he had issues with on Earth because he hated the vulnerability, and maybe also the expectations that came with it of having to do things the "right" way, having to ensure the other person feels fulfilled while never being sure how into it he actually is himself. With Rocky, it would be completely different, because Rocky has no existing expectations for what human sex is supposed to be, nor can he participate in some of the acts Grace might have had hang ups about to begin with. Rocky just wants Grace to show him what feels best for him. And Grace doesn't have to worry about not knowing how to be enough for Rocky because Rocky will tell him without judgment. They're both learning here. They're both trusting each other and nothing is going to fall apart if someone gets something wrong.
Sorry for the rant I never get this way about my favorite characters either idk what they put into gracerocky to make it like this. It's hot as hell though
UPVOTE!!!!!!!!!!!!!!!!!!!!!
