Margaret Lyonesse, first princess of Liones Kingdom and biological daughter of King Bartra Liones, is the eldest adoptive sister of Elizabeth Liones. She possesses distinctive purple hair and brown eyes, sharing a close bond with her sisters Elizabeth and Veronica.

Amidst the holy war conflict, the archangel Ludociel seizes control of Margaret's body without consent, suppressing her consciousness to use her as a vessel in battle against the demon clan. Under Ludociel's control, she fights at Camelot against foes like Zeldris. Allies, including the Holy Knights Gilthunder and Hendrickson, intervene to shield her possessed form; Gilthunder sustains injuries protecting her from Zeldris' assault.

Margaret maintains a romantic relationship with Gilthunder, a Holy Knight of Liones, a significant aspect of her life complicated by her royal status and the ongoing war. Following the holy war's resolution and the Demon King's defeat, Ludociel departs her body. Margaret returns to her duties within the Liones royal family.