Eve is a key character in the anime series 'Black Cat.' She is a genetically engineered bio-weapon with the ability to transform her body into various forms, which makes her a formidable fighter. Originally created to be a tool for destruction, Eve is initially emotionless and cold. However, as she spends more time with other characters, particularly Sven Vollfied and Train Heartnet, she begins to develop emotions and a sense of individuality. Her journey from a weapon to a person is central to her role in the series.