A Snake Falls To Earth by Darcie Little Badger, 352 pages.
Nina is a Lipan girl from the human world who loves storytelling, especially the stories that have been passed down in her families for many generations. She's also obsessed with translating the strange family history that her great grandmother told her in Lipan shortly before she died.
Oli is a cottonmouth from the reflected world where spirits live. He lives near the shores of a bottomless lake where he and many of his animal people friends have many adventures. But when a friend falls suddenly and gravely ill their two worlds will collide as Oli does everything in his power to save his friend.
This is a really neat book, in no small part because it very obviously draws a lot on Apache storytelling traditions. The result is a very unusual feeling book that kept making me think of weaving. I really enjoyed it, and will probably read it again at some point.
Side note: I love the cover on this book