Wow your characters have a lot! I want to comment here so I can read their profiles later. I will edit this message with my thoughts later.
Kestrel is a beautiful character design, Starling as well. I love Xela's horns!
Edit: Xeo and Xela's relationship is very sweet, I love sibling dynamics very much. The notes on horns and feathers are very interesting, too, as are they realistic. I did not realize at first glance how small Xela is compared to him! His dice collecting habit is very relatable, I love collecting dice, too, there are so many experts at making custom dice -- I want to get a custom set inspired by my OCs someday. The phoenix-dragon abilities are also very cool, and he feels very special with them as the last of his kind. ( ;n;
Xela birdwatching is lovely as I enjoy identifying birds where I live. Only I wish I had a bird of my own, Napalm is adorable! Xela reminds me like my younger self somewhat. I hope wherever she is in her story, she is doing well!
I'll see if I can come back again later to read more on your other OC! ^^