In the Exiles of Eire universe, Brigid is portrayed as a Aos Si queen and Daire's loving aunt. She'll play a much bigger role in the rest of the series.
The figure she's based on is an Irish goddess of wisdom, poetry, healing, protection, blacksmithing and domesticated animals. Her sacred holiday is Imbolc, a festival that marks the beginning of Spring. She's said to have invented the practice of keening--wailing in grief over a dead person--when her son was struck down in war. Many depict her as having similar triple qualities as other goddesses like Morrigan from Irish lore and Hecate from Greek lore.
One of Ireland's major saints is also associated with Brigid however, St. Brigid of Kildare, who is given the same attributes as the ancient goddess. It's led many to question the saint's historical existence--at least the way she's portrayed.
Regardless, she has a fascinating history and is my personal favorite of the Irish pantheon.