Subject Echo was one of the first of five test subjects for the "Doll" program created by Ophelia Marcellus, along with the notorious Alpha, Bravo, Charlie, and Delta. Out of the five early test subjects, all were female, and only two are alive today. Alpha and Bravo were killed in the initial testing and Delta was euthanized when she was deemed brain dead. Charlie was unstable and left for dead on a mission, and Echo was frozen once the program had been deemed a success.
The "Doll" program is now back into full swing as part of Cerberus and Abstergo Industries. Echo 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, Echo is imprinted with the personality of Ariana Valentin, a personality artificially created with Dr. Briella Turner's genius, Katie Birchall's friendliness and apathy, and Olivia Creed's charm. 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 her son, Malcolm.