Fillia was born in Kelsingra some time after the events of the Rain Wild Chronicles. As both her mother and father are Elderlings and dragon keepers to two different dragons, Fillia has been changed by both Sintara and Fente. The two dragons do not coordinate their efforts, and so Fillia displays characteristics of each dragon in discrete locations: she has both blue and green scales, two different ear shapes, and gnarled feet that prevent her from walking freely.
When Fitz arrives in Kelsingra and heals Phron, Thymara and Tats approach him to ask if he can heal Fillia as well. Fillia is delighted to have the opportunity to direct her own changes. She requests thick hair, specific scale patterns, and straightened feet.