Keith Violet is a female clone engineered by the Egrigori organization using genetic material from Keith White. As the sole female member of the Keith Series clones, she endured bullying from the male clones during her youth, fostering deep existential doubts about her identity and purpose. These doubts drove her to consult Mamma Maria, a fortune teller, seeking an answer to whether she possessed a soul.

She first met the original four ARMS subjects—Ryo Takatsuki, Hayato Shingu, Takeshi Tomoe, and Kei Kuruma—during the events in Aisora City. There, she and the other Keith clones oversaw Egrigori operations involving the captive Katsumi Akagi, whom the ARMS team believed dead. The Keith clones departed by helicopter, challenging the ARMS subjects to pursue them to America.

Like all Keith Series clones, Keith Violet was implanted with an ARMS unit, granting her superhuman abilities. Her ARMS transformation manifests as the March Hare. In this form, her body takes on a crystalline, reflective structure, functioning as a living optical amplifier. She seeds the air with nanomachine particles mirroring her crystalline composition, enabling sophisticated light manipulation. This power allows her to redirect, amplify, and focus light into lasers following unpredictable paths—an ability designated the Evil Eye of Balor. The only warning of an attack is a faint air distortion as the nanomachines activate. Her control over light extends beyond offense; she can generate realistic holograms of people or environments for deception and bend light around her body to conceal her location.

Keith Violet shares the psychological directive programmed into all Keith Series clones: an imperative to minimize destruction, originating from Alice's will. She feels compelled to obey this directive even when it conflicts with her personal inclinations or judgments.