Heith Velvet is a member of the Freya Familia, serving as the leader of its medical team. She is a young woman with light red hair typically styled into two ponytails. Her attire frequently includes a red and white apron reminiscent of a nurse's uniform, which bears the emblem of her Familia on the shoulder. She is described as being slightly taller and somewhat older than the adventurer Bell Cranel. A notable and persistent feature of her appearance is her exhausted expression, a direct consequence of her demanding role.

In terms of personality, Heith is almost perpetually seen looking tired and is known for voicing complaints about the constant need to heal other members of her Familia, particularly after their rigorous daily training sessions. Despite this frequent grumbling, she takes her responsibilities with the utmost seriousness and dedicates significant effort to caring for those under her charge. She is deeply loyal to Freya, carrying out every order from her goddess dutifully and without question. This loyalty is so profound that she views anyone who opposes Freya with contempt. She shares a close relationship with Horn, considering her a friend while also expressing jealousy towards her. Heith demonstrates a practical and understanding side as well, showing compassion towards Bell and not impeding his movements when she might have been expected to. She often fails to comprehend the relentless drive for greater power exhibited by her fellow Familia member Ottar, believing he is already strong enough, and she frequently questions and scolds him for what she sees as an indefatigable and sedulous pursuit of more strength.

Heith's background within the Freya Familia reveals her evolution as an adventurer. Initially, she underwent the same intense baptismal training as the Familia's other fighters. However, she eventually recognized her limits as a front-line combatant and made the decision to step away from direct battle. She then focused on becoming a healer, a field in which she proved to be exceptionally gifted.

Her role in the story is primarily defined by her position as the head of the Freya Familia's medical group. Her abilities as a healer are among the finest in the world, ranking just behind the renowned healer Airmid Teasanare. While Airmid surpasses her in raw healing effect and output, Heith is noted to have superior endurance and combat aptitude. She also boasts a larger reserve of mind, the mental energy required for magic, than most mages and healers of a similar level.

Heith possesses several notable magical abilities. Her primary healing magic is Zeo Gullveig, a powerful spell capable of easily restoring someone from the brink of death. She also wields Earth Gullveig, a healing spell that can be cast on herself or others to provide automatic and continuous recovery from injuries as long as it remains active. This spell is limited only by her reserves of mind. Her skill set includes three known abilities: Malditas, Freya Hrímnir, and Life Folkvanger. Additionally, she has acquired development abilities such as Mage, which enhances the power and range of her magic and makes its use more efficient, as well as Healing and Healing Power. In combat, she wields a staff.

Throughout the events leading to the fifth season, Heith remains a steadfast and critical asset to the Freya Familia, ensuring its members can endure the harshest of battles through her exceptional healing magic. Her dedication to her goddess and her colleagues, while often expressed through complaints, is absolute.