Aya Brea was born in Boston, Massachusetts on 20 November 1972. She is of mixed ethnicity; Her father (name unrevealed), who is a journalist, was white, while her mother, Mariko, was Japanese. (Mariko was also the name of a character in the novel/film version of Parasite Eve.) This gives her a unique appearance as she boasts many Asian facial features, such as the shape of her face and eyes, while possessing typically Caucasian coloring, including blue eyes and fair blonde hair. She had a sister named Maya who, along with her mother, died in an automobile accident in or around December 1977.

Aya studied criminology at the University of Virginia and was involved in their ROTC program, but any record of military service is never mentioned within the game. She later became a detective with the NYPD 17th precinct. Within the first 6 months of working at the precinct, Aya became involved in an incident known as the New York Blockade Incident to the general public. As an officer, she became part of the "father and daughter" team where she was partnered up with Daniel "Bo" Dollis, a veteran cop, who can be considered overly protective of her at worst. On December 24, 1997,