- The daughter of David Cain, one of the world's foremost assassins, and Sandra Wu-San - a martial artist chosen for her superior genetic potential, who would go on to achieve infamy (and incredible skill) under the name of Lady Shiva.
- Latest in line for a series of ongoing experiments to create the ultimate martial artist, one whose very language is the motions of violence. Referred to as "One Who Is All", Cassandra was to eventually be shaped into the perfect bodyguard for Ra's al Ghul.
- Trained by the League of Assassins; including her father and such fighters as Bronze Tiger, Merlyn the Archer and Alpha.
- Considered ready for her first assassination at the tender age of eight, Cassandra was set upon an unfortunate target named Faizul. Innocent enough to believe this just another part of her training, a sort of game, she was unleashed upon the man and tore out his throat in a single movement.
- Using her unparalleled talent at 'reading' her opponents, she observed Faizul's body language as he died, and suddenly understood the intimate horror of death. Shocked, and emotionally scarred, she ran from her father and the League - escaping through a combination of luck and excellent training.
- Has spent nine years as a runaway, sleeping in whatever temporary means of shelter are available and living off her wits upon the street. Acquaintances have been fleeting at best - unexposed to social situations as a child, she is a mute - and has simply been surviving as best she can.
Raised by a corrupt but calculated mind, Cass was never intended to be a human being, at least in any recognisable sense. Though she has escaped her purpose as a living weapon, at this stage she is little more than a broken semblance of a person. Not given to trust and a stranger to the concept of pretence, she wears a damaged heart upon her sleeve, rarely communicating and - thanks to a severe disorder - never doing so verbally. Her social skills are non-existent; she was taught to speak through violent actions.
Beneath it, however, lurks a girl who could be so much better. Horrified by the taking of her first life, she bears a deep-rooted sense of morality that even the most terrible upbringing has not been able to entirely squash. Though she may herself occupy the lowest rung on the social ladder, she is keen to protect and aid the less fortunate, and could never be described as selfish. Frightened of what she is, unversed in the ways of the world and the value that other people might represent, she at least has the spark of righteousness.
On the rare occasion she may let her guard down enough to show her more human qualities, Cassandra expresses herself through gestures and meaningful glances. Illiterate, she is unable to write out her more complex thoughts or feelings, restricted entirely to what can be achieved through body language. She understands well enough, though; not just what she hears, but what she sees. Thanks to the tuition of the League of Assassins, she is able to read others' intent and emotional responses by the tiny nuances of their form.