Tart, commonly called Tarte, hails from a destitute village. Frailty led to her abandonment in the wilderness, near death, until Lugh Tuatha Dé discovered her. He offered sustenance and recruited her by expressing a genuine need for her abilities. This rescue forged her unwavering lifelong devotion and core motivation: absolute loyalty to Lugh as both savior and master.

Publicly shy and taciturn, Tart harbors fierce protectiveness toward Lugh alongside deep-seated insecurity. She suffers recurring night terrors, seeking solace by sleeping beside Lugh—a habit persisting even after the nightmares fade. Her competitive spirit surfaces in culinary pursuits, where her cooking rivals noble-house chefs; she meticulously replicates dishes Lugh favors. Threats to Lugh’s safety or reputation trigger palpable aggression, unleashing killing intent and employing torture during interrogations. She displays cunning through calculated actions, like stealing kisses under the guise of mana replenishment. Academically gifted, she ranked sixth among elite noble students in law, history, and mathematics.

Tart’s S-Class physical abilities grant superhuman speed, strength, and reflexes surpassing knight-order vice-commanders. She wields a spear with precision, countering multiple high-tier opponents or executing rapid thrusts that overwhelm adversaries like Lugh. She handles recoil-intensive firearms one-handed during spear combat. Wind Magic enhances her mobility for acceleration, aerodynamic barriers, and sensory concealment. Lightning Magic enables lightning-speed movement and stunning electric discharges, though it rapidly drains stamina. Lugh augmented her further via 【My Loyal Knights】, granting: 【Beastification】 (S-rank fox transformation boosting physical traits and inducing pheromone-based intoxication), 【Rapid Recovery】 (S-rank stamina/mana regeneration), 【Possibility Egg】 (A-rank adaptive skill), and 【Limitless Growth】 (B-rank breakthrough of natural caps). She also possesses 【Mystic Eyes】 for long-range, mana-perceiving vision and 【Squire's Devotion】—an A-rank skill reviving Lugh at the cost of her life while amplifying their linked abilities.

Her development focuses on emotional growth. Early unrequited feelings toward Lugh, exacerbated by his brothel visits reducing her to tears, evolved into romance facilitated by Dia’s acceptance, culminating in her status as Lugh’s fiancée. Encouraged by Lugh to voice emotions, she transitions from subservience to confident assertiveness, though teasing from him or other fiancées flusters her. 【Beastification】 unleashes suppressed desires, manifesting as bold aggression—like physically overpowering Lugh—contrasting her usual reserve. Combat evolution sees her master granted skills to rival Lugh’s full strength while transformed. Familial integration includes bride training under Lugh’s father, emphasizing self-defense to mitigate assassin-family vulnerabilities.