What is a Wind-Rider? They've been around longer than humans. After their numbers dwindled they learned to hide in plain sight among us. They can look like us, talk like us, act like us. As long as we are no threat to them they are no threat to us. There are a few however who would like to see that change and take back the world that was once theirs alone.
In the book Cold Encounters you get your first glimpse of one when she is called by someone to help. Amber isn't happy that a human knows she exist.