Birdy

baby Eridians are tiny and vulnerable, so some of their first instincts are "get under something, your very small and you're gonna get squished or eaten!" when pebbles first hatch they want to get under an adult- usually a parent- but the pebbles don't know how to walk immediately so the parents will walk and stand over them. this is basically how babies and parents' bond. ducklings know the one they follow is mom, and pebbles know the one standing over them keeping them save is mom <(gender-neutral)

So! I think Grace probably has some moments of feeling a bit overwhelmed, maybe in new places or big crowds. it's an intrinsic primal survival instinct, Eridians literally grow out of it when they get big and won't get trampled. the artificial growth of Graces body kinda skipped all that so I think some of the "I am so small and fragile" feelings remain. he might also forget how big he is while really panicked and wedge himself somewhere and get stuck.