Felicia possesses long blonde hair and light blue eyes, noted for her well-endowed, beautiful appearance and attire fitting the world of Yggdrasil. An Einherjar warrior maiden wielding magic for the Wolf Clan, she is the daughter of its murdered former patriarch. Her inadvertent role in significant family tragedy stems from performing the Gleipnir ritual with a divine mirror, summoning Yuuto Suoh from another world; this act resulted in her father's death and caused her biological brother, Loptr, to defect from the clan, blaming her.

After Yuuto's arrival, Felicia and her people took him in, forming a close bond. When Yuuto ascended to become Wolf Clan patriarch—a position Loptr believed should have been his—Felicia remained fiercely loyal. She firmly rejected Loptr's subsequent request to abandon Yuuto and join the Panther Clan. Felicia wields the rune Skírnir, the Expressionless Servant, granting superhuman speed, and fights primarily with a whip, demonstrating great skill. The hidden magic Gleipnir, used to summon Yuuto, remains a significant aspect of her abilities.

Serving as Yuuto's deputy and sworn younger sister, Felicia deeply respects him as a harbinger of victory and harbors strong romantic feelings. She frequently attempts to seduce him despite his explicit rejections, efforts that persisted until Mitsuki Shimoya, Yuuto's childhood friend, arrived. Felicia maintains a generally happy demeanor, aligning with the Latin meaning of her name, and is rarely seen without a smile. She exhibits warmth toward Yuuto and actively seeks to understand him better, though she is not his primary romantic interest.

Beyond combat, she accompanies Yuuto and Horn Clan members during strategic movements. Her loyalty and the emotional conflict stemming from her family tragedy and duties remain defining traits.