If our muses haven’t fused in canon, send “Fuse with me!” and I’ll tell you about them!
I’ve waffled with this the various times you’ve sent me one for a meme similar to this, but I’m going back to what feels right: Moonstone. I think she’d act a lot like this, especially the first time she comes into being. But I think she’d look a lot more like this, and this (though maybe more with a nice poofy jacket and matching pair of pants now with their new forms!). Her size is about what you see in the first comic.
That third picture is especially important though, because what really holds Moonstone together (aside from her undying loyalty and love for Steven), is that longing for what once was, what they can’t have anymore, and eventually, an acceptance of what IS now. Moonstone is a journey, and I like to think she has a happy ending.
She still likes taking long flights over Beach City and watching some of the nicer memories in her head via her gem.