David Cain is a psuedo-retired master martial artist and assassin who was famed for being able to take out some of the most famous and powerful people on the planet, no matter how seemingly impossible the task.
Name: David Cain
Marital Status: Single
Exceptionally meticulous, Cain's success can be partially attributed to his painstaking preparation, always planning far ahead for any contingency: hence his decision to train someone to be his partner and eventual successor. He had made several attempts in the past, training young children, but found every one of them to be a failure. The closest success he had was a child that was later named The Mad Dog. While he was highly skilled, he was also a feral insane child who was more animal than human. Giving up on this child, Cain decided that the answer to his problem lay in genetics. If he was to accomplish his goal, he would need to have a child of his own, whom he could train from the moment he or she was out of the womb but in order to do this, he also needed to find a woman warrior worthy to mother said child. David Cain found the perfect mate in Sandra Wu-San. While visiting he witnessed Sandra and her sister Carolyn, sparring in a martial arts tournament. While both women were highly accomplished fighters, Cain saw a flame in Sandra which he felt he shared. Cain decided to spark it by removing the restraint that held her back. One fateful day, Sandra found the bloody corpse of her sister, murdered in cold blood.
Discovering that David Cain had been the one to kill her sister, Sandra Wu-San hunted for the murderer, only to be lured into an ambush by Ra's al Ghul's League of Assassins, of which Cain was a member. Although she lost the battle, in the heat of the moment, Sandra realized how much she had held back when fighting Carolyn and got a taste for just what heights she could attain with more experience--her life now had purpose. However, Cain exacted a price for sparing Sandra's life after the battle with the League. In order to be reborn as something new and terrible, Sandra agreed to bear Cain's child and leave that child for him alone to raise. The child who would later be named Cassandra Cain, was to be Ra's al Ghul's "One Who Is All," a perfected bodyguard whose only native tongue was an instinct for hand-to-hand combat and the ability to read people's intentions simply by observing their slightest muscle movements. Cain trained Cassandra in every imaginable form of violence, from hand-to-hand combat to weapons and explosives. To further her skills, Cain never taught her how to speak; instead, physical movement became her language – she learned to read a person's body language as well and easily as other people can understand speech. This skill led Cassandra to be able to predict exactly what her opponents were going to do, sometimes before they knew it themselves.
When she was 8 years old, Cain took her to kill a businessman. After she did it, she "read" him as he died, she saw death as the man saw it. "Terror and then... nothing". In addition to scarring her emotionally, she realized murder, like Cain's profession, is wrong, and she ran away from her father. Cain was surprisingly devastated by her disappearance and has never been the same since. He has never quite given up hope that someday she might return to his life. While Cain is not that good of a father, he has shown that he does care deeply for Cassandra; he even began to cry slightly when he heard her speak for the first time, even if it were merely the word "Stop".
Cain was the one who framed Bruce Wayne for the murder of Vesper Fairchild, partly because Lex Luthor had hired him to do so and partly to see if Batman was worthy enough of raising Cassandra. For a time, he felt that Wayne had proved he was incapable of it, as he rejected the help of the Bat-Family and went out on his own, but as Cain and Batman fought shortly before the conclusion of this story arc, Bruce Wayne vowed he would no longer be that way. Believing Batman had succeeded in proving himself, Cain cleared Bruce Wayne's name by turning himself in. David Cain willingly stayed in prison, although he demonstrated repeatedly that he could escape if he wished, until he was freed during a plot by a manipulated and drugged Cassandra and began working with Slade Wilson to create an army of girls similar to Cassandra out of the numerous 'failures' he had trained previously.