Subject Juliet was part of the second set of test subjects for the "Doll" program created by Ophelia Marcellus. The second part test consisted of India, Juliet, Oscar, and November. Out of the four subjects, only one has been unfrozen (Juliet), and November is only a hypothetical. Oscar is the only male to date, and has been scrapped for the most part, as his mind never took to the initial imprint.
The "Doll" program is now back into full swing as part of Cerberus and Abstergo Industries. Juliet has been awakened and can be imprinted with identities, personalities, skills, and false memories in order to be sent into the galaxy on engagements; a term used by Ophelia for an Active's mission.
Currently, Juliet is imprinted with the personality of Serendipity Kim, a personality artificially created from her original personality, except her memories of her boyfriend wiped and the memory of being captured by Cerberus to begin with. She also has increased reflexes for a human, and possess no biotics. She is also on a prolonged and possibly permanent engagement created by Ophelia for Lament, one of Colton's employees.