While attempting to track down her father, David Cain, Cassandra Cain stumbles upon a mysterious woman in the midst of executing several potential experimental assassins. It's revealed that, Marque, as she calls herself, was one of Cain's original test subjects pre-dating even Cassandra herself. Motivated by a pure hatred and bent on revenge, Marque will stop at nothing to kill the man she holds responsible for her shattered childhood. Unlike Cassandra, Marque has no reservations about killing any, and everyone who gets between her and her ultimate goal.
It is later discovered that Marque shares not only the same fighting abilities as Cassandra but is also a DNA match. Although it has yet to be revealed who Marque's mother is, or was, David Cain is her confirmed biological father. Making her at the very least, Cassandra's half sister. However due to Cassandra's interference in her plot against Cain, Marque has sworn off any relation to her sister and has declared her now and forever, her enemy.