It all started with an unnamed incident. The actual incident is not known much, but it involved Bond being transported to Third Earth and vice versa with the ThunderCats on Earth. When he and Cheetara were captured by Miles Warren (the antagonist responsible for the Clone Saga in-universe) and used sperm from him and an egg from the inside of Cheetara to create a full being mixing the two genes. After the incident, every party assumed everything for Warren's research was lost forever, but he somehow survived the descruction of his lab and escaped with the already developing fetus itself unscathed (the fetus being teleported to a secret base at the last minute). He managed to gather a few scientists in a secret base for nine months and, just as she was ready to be born, a sympathetic scientist who was disgusted at his plans to make her the ultimate soldier took the baby away killing everyone in sight and, despite managing to narrowly place her on the doorstep of a church, she ended up being shot and basically dragged herself to get the baby to safety. As a result, she was adopted by the nuns to be placed in the church orphanage. When she was five, she managed to recite everything in the Bible, read every book she could get her hands on and aced various math tests with ease. She was seen as sort of child prodigy but barely made any friends, especially since various children saw how she looked and stayed away from her. A few months later, she was finally adopted by two loving parents. Finally, she and her adopted parents moved to Fairfax, Virginia. Out of concern as to her apparent half-human/half-cat appearence, they somehow managed to acquire a serum that would at least temporaily give her a full human appearence for twenty-four hours.
Over the years, she was still considered a child prodigy but also anti-social. She even earned herself a few enemies but she always talked down at every bully, basically openly insulting them and, as a result, got into fights even if she never intended to. In what she considers to be a running gag, she gets hit first.
Her hobbies over the years have included archery lessons, paintball and karate. She discovered that she had super speed at the age of thirteen, much to her confusion. Concerning being a half-human/half-cat person, the only thing she's hugely curious about is who her parents are; she has no idea as to how she had been conceived. She doesn't care what people think and if she hears racist remarks or the like, she'll openly insult them back and pound them if they attack her. A few graduations later, she left on her own to persue a goal: To get a licence to kill. During her high school and college years, she had read about spies and espionage. Fascinated by the prospect of working for a secret service, she felt that she could do a great service to the world. However, not wanting to work for a specific organization (and hating the idea of being given specific instructions according to them and not her instincts), she decided to become a freelance spy with a licence to kill. She did, and thus Eve Halle was born. She has accomplished twenty missions so far and killed fifty people in the process (basically flunkies and madmen). Despite all that, her greatest desire to know and see her real parents.
She can appear to be cold and really someone you can't trust but at the same time, she can be willing to communicate with others eye to eye. She's knowledgeable, she can fake stupidity, insanity, and gullibility. She even tricks and uses people to accomplish her missions by giving false information about herself. However, when confronted by her real parents, her personality traits will possibly disappear completely when she's face-to-face with either James or Cheetara; double the shock if the both of them are together.