O'Brian is mixed race, with black and white ancestry. O'Brian began studying martial arts at five years old, and at age nine earned her brown belt in Shorei Goju Ryu
Karate. Throughout her youth, she participated in numerous sports programs and also in music programs as a
percussionist. She attended
Indiana University Bloomington, majoring in
psychology and
Germanic studies. She was one of the first members of the university's short-form improv troupe Hoosonfirst. She received law enforcement certification through the university's Cadet Officer Program. At university, she received her
black belt in
hapkido through the US Hapkido Federation. After graduation, she was a
police officer for seven years at the Carmel Police Department in
Carmel, Indiana, including the department's Crisis Intervention Team, which specialized in helping individuals with various conditions such as psychosis, depression, Alzheimer's, and autism. She obtained her
personal trainer certification and began competing in
bodybuilding figure competitions, and training at the Indy Actors Academy. She competed twice in figure, in September 2014 and May 2015, but stopped because of the expense and because she did not want to take steroids like some other competitors. In 2016, O'Brian moved to
Los Angeles to pursue a career in film and television. While waiting to land a role, she worked with the
University of California, Los Angeles Martial Arts Program, helping with self-defense classes and instructing the Hapkido program. Through the same program she also studied
Muay Thai and
Brazilian jiu-jitsu. ==Career==