Rookie
Julien is introduced as a rookie in the series pilot and was paired with training officer Danielle "Danny" Sofer. Due to his Pentecostal beliefs and moralistic view of police work, Julien often clashed with his fellow officers.
Early in his career, he observed the Strike Team stealing two bricks of cocaine during a bust and reported this to Captain Aceveda. Danny was enraged that Julien would become a "rat" and told him, "This is a brotherhood." Aceveda warned Julien that the charges were serious and not to pursue them, but Julien went over his head and informed Internal Affairs. Little is known about Julien's life before the series, in the Co-Pilot episode, it is shown that Julien's first day was working in The Barn before it opened. Which shows him as his first day as a police officer.
Read more about this topic: Julien Lowe