Miru, together with her sister Meru, were both Zev priestesses in the times long gone. Not much is known about the circumstances in which they became ancestral spirits, protecting the future generations of Zev from the Deepwood.
Maybe the sisters will share their story one day.
Similar to her sister Meru, she became the guardian spirit of a Zev girl, R’Shiru Oddmane. While both Meru and Miru want the best for their summoner, they often put themselves into dangerous situations, taking advantage of their immortal magical bodies to do activities they were unable to do in their lifetime.