Vanessa Diodati led Noble Red, a faction emerging from the ruins of the Bavarian Illuminati after Adam Weishaupt's demise. Her Indian-British heritage originated in Stanley, Hong Kong, where her father directed a film production company. Both parents were Illuminati members, immersing Vanessa in the organization's activities from childhood. She initially forged a promising career as an engineer developing Faust Robes, until a near-fatal accident left her body irreparably damaged.

Alchemists salvaged her by grafting her consciousness onto a mechanical "silhouette body" using Faust Robe technology, transforming her into an alchemical cyborg. This mechanical form violated the Illuminati's doctrine of physical perfection, leading to the stripping of her status and achievements. Learning her parents authorized this dismissal shattered her self-worth, causing her to view herself as "scrap metal." During subsequent experimental procedures, she bonded with fellow test subjects Millaarc Cranstoun and Elsa Bête. After the Illuminati's collapse, the trio escaped confinement and formed Noble Red, with Vanessa becoming leader as the most senior member despite lacking superior combat prowess or innate leadership traits.

Vanessa projected a calm, mild-mannered exterior yet concealed a shrewd, ruthless personality willing to harm or kill innocents to achieve Noble Red's goals. She demonstrated genuine care for Millaarc and Elsa, acting as a protective older sister. Their primary objective was harnessing divine power to restore their original human bodies, driving them to collaborate with Fudou Kazanari, who offered protection in exchange for aiding his schemes.

Her cyborg body served as her primary weapon, enabling attacks like projectile fists retracted via cables and hover capabilities via leg-mounted devices. A high-density energy field held her form together indefinitely, though its output remained inferior to Faust Robes. A critical weakness was her dependency on rare RH-Xxoyle blood—found in roughly one in a million people—to maintain functionality. Key combat systems included the Collider, generating an energy barrier for defense, and the Harmonic Scalpel, high-frequency emitters in her arms capable of severing molecular bonds.

In Symphogear XV, Vanessa infiltrated Los Alamos National Laboratory to steal the Vambrace of Shem-Ha per Fudou's orders. She later used fragments of the Shénshòujìng relic to construct a Faust Robe that restrained Shem-Ha upon her rebirth. After Fudou betrayed Noble Red, Vanessa and her allies were killed by Shem-Ha.

Shem-Ha resurrected them as perfected cyborgs to serve her agenda, reconstructing their bodies and eliminating their blood dependency. This transformation granted enhanced capabilities, including simultaneous weapon deployment and energy absorption from the Lunar Ruins to achieve an "Ultimate Cyborg" form. However, the loss of her remaining humanity shattered Vanessa's self-worth, plunging her into madness. She participated in Noble Red's assaults under Shem-Ha, including the destruction of a lunar rocket at Tanegashima Space Center.

During the group's escape via a teleportation vial, Tsubasa Kazanari intercepted them, spilling the vial's contents and transporting Vanessa alongside the Symphogear users to the moon. Her story concludes stranded in this desolate location, her ultimate fate unresolved.

Vanessa's character concept and surname reference Frankenstein's monster, aligning with Noble Red's thematic ties to mythological creatures—her cyborg nature evokes Frankenstein, Millaarc represents vampires, and Elsa embodies werewolf lore.