Mercedes Marten is the daughter of Grende Hearthstone of the House of Marten and captain of the Enlistment Corps. She idealizes knights, knighthood, and wished to be placed in charge of her own company of knight as her two brothers had. However her father wished to marry her to an influential noble or royal from a neighboring demesne to firm up the power base of the House of Marten. Aware of her inexperience and lack of skill required to lead others Mercedes trained until she was reasonably able as a knight.
When the dragon attacked Gransys, Grende Hearthstone saw it as an opportunity to greatly increase the power of the House of Marten. However he did not want to send either of his valued sons but knew he had to send someone who was closely related to him and of suitable position or Gransys might take offense. He sent Mercedes knowing they would never allow a women on the front lines. Mercedes was unaware of this and set off for Gransys thinking that her father had finally given her his approval.