Rally's father is Indian and her mother was English. As a result, she has dark blue eyes, dusky skin, and dark hair.
Her father was an Olympic-level marksman who taught Rally about firearms while running a gun store called Gunsmith Cat in Chicago. Her mother, who had wanted Rally to be a violinist, opposed everything to do with guns and eventually was murdered at the store by robbers when trying to file divorce papers on her husband. After that incident, her father disappeared to search for her mother's murderers, and she was supported through her teen years with money sent from him, but as the money stopped coming, Rally took up bounty hunting as a means to find him, but sadly turned up with no results. She then took over the store as her own venture, and recruited May as an assistant. Upon making May a partner, the shop became known as "Gunsmith Cats".
A bit reserved when it comes to men, Rally feels most comfortable when discussing firearms. While all her IDs state that she is 21 (the age necessary to sell firearms) her actual age is 19. Her weapon of choice is a CZ-75 First Edition, built by Česká zbrojovka Uherský Brod in the former Czechoslovakia. Rally drives a blue 1967 model Ford Shelby Mustang Cobra GT-500 with white racing stripes, which she cherishes until its destruction in Gunsmith Cats BURST, when it is replaced by a heavily-modified Ford Mustang II Cobra. When quarreling with Rally, May implied that guns and cars were sex substitutes for the virginal Rally; there is arguably an erotic undertone to her fondness for guns and cars.
She is highly skilled in hand-to-hand combat, with great speed and physical agility, and is an expert but reckless driver. Although she does not always respect the letter of the law, she has a strong moral sense of right and wrong and is reluctant to kill unless absolutely necessary. An excellent marksman, she often targets her opponents' trigger fingers or crucial components of their guns in combat rather than going for a lethal shot. As a result, she has sometimes been hunted by criminals angry at their mutilation at her hands.
Rally also usually carries a .25 DuO (made by the same company as the CZ-75) with the trigger guard removed, mounted on a spring-loaded frame strapped to her arm for quick access in a tight spot. When her CZ-75 has been unavailable, she relies on a SIG P210, another very high quality weapon, and sometimes carries a back-up gun in an ankle holster. She keeps a precision rifle and shotgun in the trunk of her Shelby; these have included a Walther WA2000 and a SIG 550 Sniper variant. Her first gun, given to her by her father, was a AR-7, a small .22LR rifle that can be disassembled and the components stored inside the buttstock; she uses this from time to time. Other guns Rally owns and cherishes are a 1960 Colt .25 pocket model, a Beretta 84F, a Walther P38, a Parabellum P'08 (Luger), a Colt Lawman Mk.3 and a Browning Hi-Power. She has occasionally used other weapons, including a Glock-19 and an RG14 "Saturday night special" revolver when she was completely devoid of other weapons, and she is an expert shot with any firearm she has been shown using.
It is not clear from the Japanese whether Rally's name is intended to be "Irene" or "Eileen" but the official English translation uses Irene. In several European editions of the manga, most notably in the Italian one, it is "Aileen". Since L's and R's are mostly interchangeable in Japanese to English translations, the main character's name is often translated as Rally Vincent, and this has become the standard. However, at the 1993 Anime America convention Kenichi Sonoda, when asked a question about the character, started his answer with "It's Larry, not Rally." This is further backed up in the manga where in one scene she is receiving a fax from Becky (about Riff-Raff), and the note scrawled on it addresses her as Larry. Sonoda also made mention that Rally is a lesbian, but is celibate.
A word of note - the Rally Vincent portrayed in 'Riding Bean - the one that is Bean Bandit's partner - is a prototype version of the Rally shown in 'Gunsmith Cats'.