Eva Durix serves as the main antagonist of the Virtua Fighter anime series. She is a robotics scientist of German nationality who becomes driven by a controversial theory that she once presented to the scientific community. Her core belief is that martial artists and fighters possess immense potential that is fundamentally limited by their human emotions, including their conscience and fears. She argued that by removing these psychological traits, a fighter could become the perfect weapon, far more dangerous and effective than any standard trained soldier. When her colleagues dismissed this theory, she did not abandon her goals but instead sought other means to prove her claims.

To continue her research, Eva Durix allied herself with the Koenkan ninja clan, who provided her with the resources and backing she needed. Her ambition eventually captured the interest of the powerful Rafale company, which supplied her with additional funding. Eva is characterized by a cold, calculating, and manipulative personality, showing a distinct lack of empathy for others. She is willing to go to any lengths to achieve her goals, treating human beings as little more than raw materials for her experiments and showing no genuine concern for the suffering she causes.

Physically, Eva is a slender woman with short green hair and distinctive yellow eyes. Her most notable physical trait is a teardrop-shaped mark located below one of her eyes. She is typically seen wearing a professional outfit, often a women's business suit consisting of a brown miniskirt paired with a purple shirt and a mauve tie. On other occasions, she wears a researcher's gown, consistent with her scientific background. Unlike most antagonists in martial arts-focused narratives, Eva does not directly engage in combat. However, through her extensive research and observation of various fighting styles, she possesses a high-level theoretical understanding and keen analytical eye for martial arts techniques.

Eva's primary motivation is to create the perfect soldier, an ambition that drives the entire plot of the series. To this end, she recruits the ninja Kage-Maru to abduct Sarah Bryant, a young woman from the wealthy Bryant family. Eva uses Sarah as the prototype and basis for her ultimate creation, a powerful robotic weapon she names Dural. She also briefly assists the antagonist Liu in a failed plot to brainwash Pai Chan. After the destruction of her first Dural model, Eva unveils an upgraded version, Gold Dural, and captures several of the world's most skilled fighters to study their techniques. Her quest for power is fueled by a desire to prove her theories correct and gain recognition for her work, regardless of the ethical costs.

Regarding her relationships, Eva often interacts with Kage-Maru as a mercenary hired to perform her abductions. She has a close professional relationship with Liu, another antagonist, and at one point brainwashes Pai Chan on his behalf. Her dynamic with the protagonist Akira Yuki is one of direct opposition; she views his compassion and fighting spirit as weaknesses to be exploited, while he represents everything her philosophy rejects. There are also hints in her behavior that suggest a potentially close, ambiguous relationship with her colleague Ryu, including an expression of affection before her demise.

Throughout the series, Eva remains a consistently amoral force, but her character does undergo a form of development at the very end. After Akira defeats her ultimate creation, Gold Dural, she attempts to shoot the heroes in a final act of rage. The damaged Dural instead pulls her into a deep chasm. Akira grabs her hand, trying to pull her to safety so she can face justice and atone for her crimes. In a moment of grim resolution, Eva refuses his help. Having witnessed his strength derived from compassion—the very emotion she always dismissed as a weakness—she seems to finally understand the flaw in her own beliefs. Smiling, she rejects the future he offers and lets go, falling to her death.