It's nice to get Rose Quartz's past, but Ruby And Sapphire? Well, they have a love story of their own here, and one that's met with resistance and horror by the other Gems. (Although it has a lot to do with breaking conventions; this could be seen as a simple act of rebellion against fascism, or as something more. Ruby and Sapphire literally merge. I didn't read it as sexual, but I did read it as an act of love: Ruby knows that it's forbidden and does it for Sapphire's sake, anyway.)
It's not that the Gems aren't sexual at all. Rose Quartz has to have some kind of contact with Steven's father to have him, but it's all alluded to: she has to give up her body and whether or not she has sex - as humanity thinks of sex - or Gem sex (whatever that might be) , or something that's in between? It's hard to tell.
Is merging sexual for them, as well as a military tactic to create larger, and more powerful, Gems? Or are they asexual? (Again, given Rose Quartz, and Ruby and Sapphire here, we know they aren't aromatic.)
This leaves us with many questions and one answer: love. Love another, and you can do what seems impossible. In the end, that was the only answer I needed, and I ended up crying happy tears at the end of this book.
There's also a lot of playing with narratives - when a book should end and when it does, what is the proper narrative - and those mini Ruby and Sapphire's at the bottom and top of the book are amazing.
Absolutely loved this book!