She is a cloistered cleric from Erin. The Zeston family have been officials in the Eln Empire’s military for generations. The head of the Zeston family holds as much pull as the Head of the Guard in Erin, if not more. Theia ran away from her family and their worship of the lawful Saint Cuthbert.
Her and her sister, Irina, are the last living members of the Zeston lineage.