Nakoda Charday (also known as "Gran" to all the girls) is Adriane's wise Native American grandmother and caretaker who was a deep passion for animals and lives on the Ravenswood Preserve. She used to be a friend of Henry Gardener before his mysterious "disappearance". Her appearance is an older (but active) lady with a long, silvery braid, olive skin and black eyes.
Nakoda is not mentioned much in the series, but is very wise and gives very meaningful advice. It is hinted at a few times that she may know about the existence of magic. Maybe not of Aldenmor and Avalon magic, but definitely some kind (most-likely Native American magic). For example, in Circles in the Stream, Adriane tells Emily that her grandmother is always trying to talk to her about "spells" and "lucky charms". There was (and possibly still is) a rumor that she was a witch.
Nakoda's daughter is Willow Charday and her son-in-law is Luc Charday (Luc adopted the surname Charday). She asked to take care of her granddaughter Adriane while her parents were traveling all around, and they accepted, so Adriane finally would have time to settle in somewhere and make friends. In Ghost Wolf, she starts calling Adriane "Little Wolf" instead of "Little Bird" the morning after Adriane discovers her worldwalking ability.