Fal-Ys Meigis, First Princess of the Royal Capital of Mages, wields significant political authority within the royal family. She first meets protagonist Al Wayne when he accidentally thwarts her kidnapping and forced marriage, forging their initial bond. Exploiting this connection, she orchestrates Al's recruitment into royal service, strategically leveraging his unique abilities against mounting kingdom threats like monster attacks and demonic incursions.

To interact with Al unofficially while hiding her identity, she adopts the alias "Filia," using a magical hairpin to alter her appearance. As Filia, she integrates herself into Al's life and activities, her initial political motives gradually blending with genuine romantic feelings for him. This sparks a friendly rivalry with Helen Rean and Ruri, who also vie for Al's affection.

Her role extends beyond strategy as she actively confronts major threats alongside Al and allies, engaging in battles against formidable foes like the Dragon of Malevolence Ouroboros and demonic entities. Her relationship with her father, King Galan Ys Meigis, underscores her royal status and duties. Her interactions also reach Al's family, including his resurrected adoptive sister Ilvia, creating complex dynamics of loyalty and conflict involving the Evil God.

Demonstrating royal authority, magical skill, and personal vulnerability, she evolves from a figure focused on political utility to one deeply invested in protecting both the kingdom and her personal bonds, particularly with Al. She navigates treacherous waters, balancing public duties against private relationships and emerging emotions while facing external threats like the Demon King's forces and intricate family complexities.