Julien is a zealous Christian, and places moral concerns over the unblinding loyalty most officers place in their fellow officers. This has often put Julien at odds with his peers.
Julien is also homosexual. He has undergone sexual reorientation therapy at the suggestion of his pastor, and has married a woman. Julien was closeted throughout much of season one; when some other officers discovered his sexuality, his strong moral code was put at odds with his desire to keep his orientation secret. In the end, Julien chose to keep his secret over following his moral code.
Julien is married to Vanessa Lowe, the mother of a young boy caught spraying gang graffiti. His step-son's name is Randall Lowe. Before marrying Vanessa, he confessed his homosexuality to his wife. She has accepted his history.
Julien was a rookie paired with training officer Danny Sofer. He and Danny were the ones that found Nancy Reborg's body and helped her sister, Janet, to identify the body. Julien and Danny later tended a call from a young couple, Fran and Hooper, who argued that her ex-boyfriend, Lamar Tilton, had slashed the tires to their car. During questioning, Julien noted to Hooper how he could have such an expensive car and such a cheap house. They later found Lamar, who confessed to having slashed the tires of the car claiming that he had given Fran the down payment money. They arrested him and took him to the Barn.
The day after Terry Crowley's death, Danny blasted Julien for not going to the hospital like the other officers. Julien told her that he didn't knew Crowley, but he said a prayer for him. Danny reminded him that one day those other officers might save his life. They then walk out to patrol, as she reminds him that every time a cop is killed, they have to go out to remind people that they're still in charge. During their run, they attended a 911 call and found a man going through the pockets of a fallen street vendor. As they order him to stay away, he refuses to. Julien then grabs him and throws him violently against the street vendor cart. He is later reprimanded by Danny and Claudette Wyms for contaminating the crime scene.
When the vendor's son confesses that he owed money to a man called Marlon Demeral, Danny and Julien went to arrest him. As they did, Marlon's family blasted them for arresting him. After they arrive at the Barn, Officer Paul Jackson and his friends invite Julien to have a drink that night. Julien rejects them at first telling them he has to go to church. However, they insist claiming that they have to give him his initiation "b-and-b". He accepts but later asks Danny about it. She simply tells him it's something he should get over with quickly.
That night at a bar, Officer Jackson and his friends have Julien drink a whole pitcher of beer as part of his initiation. After he is drunk, they call Betty, a woman at the bar that likes cops. She kisses Julien and takes him to a back room where she gives him oral sex. As she does so, Jackson and the others looked at from a door.
Some days later, during "warrant sweep day", Julien and Danny arrested Tomas Motyashik. As he was being taken into the Barn, he recognized Julien from outside a gay club called The Abbey. Julien refuses to talk with him, but he insists. Tomas tells him that his arrest warrant is a mistake and that he should call his legal aide to verify it. Despite Danny's recommendation to not let the prisoners get into him, he does check it and corroborates Tomas' story. He is then released and, as he goes out, he asked Julien for his number, but he refused him.
When Julien and Danny were serving another warrant, a woman approached them and complained about noises from the door of her neighbor Ricky Harris. They assured her they'll look it up after they finish. When they did, they found Ricky with two friends: Monk and a third man. As Danny noticed their nervous behavior, she told Julien to check the house and he found several automatic weapons under the couch. Harris and the rest were arrested. That night, Julien visited Tomas and after assuring him he wasn't gay, they kissed and got in his apartment.
Sometime later, Danny and Julien attended a call from Dottie Cummings, who told them that her son was missing and someone was calling her for a ransom. When Danny realized that her son was dead and that somebody had stolen his body, she left Julien with her. Julien tried to help her and when the man called again, she recognized him as her ex-boyfriend, Henry. Julien then arrested him and took him to the Barn.
Julien was present at the raid on the Armenian Mafia led by the Strike Team. After that, he observed the Strike Team stealing two bricks of cocaine from the dealer's stash. Back at the Barn, he verified with Officer Lily Cacuzza, who was in charge of the evidence log, to see if there were cocaine bricks missing. After realizing he was right, he wondered what to do. Not sure, he asked Claudette Wyms for advice. He later reported this to Captain Aceveda.
When he and Danny intervened with Deena, who had stolen the Lincoln Navigator where the Strike Team had hidden the cocaine bricks, he went against Danny's wishes and reported it. After Deena gave some information to Aceveda, Julien was among the officers that raided Freddie's house after the Strike Team arrived. Later that night, Julien stopped by Tomas' house and told him they couldn't see each other again. Tomas confronted him with the feelings he had, but Julien told him that it wasn't right. As he was about to walk out, Julien came back and started kissing Tomas.
Although Aceveda told Julien that the case fell because the drugs were never found, Julien decided to take it further and reported it to Internal Affairs. When Aceveda found out about it, he blasted him for it. Also, when Danny found out about it, she told him it was a mistake. Julien was angry that everyone went at him for doing what he thought was right and eventually told Danny what he saw.
Julien's homosexuality placed him at great odds with his religion, even to the point that he didn't wear his vest to a bust, hoping the criminal would kill him. Through his pastor, he eventually went through sexual reorientation at his church and married the mother of a young boy caught spraying gang graffiti. Tomas was eventually arrested and when Julien refused to continue their relationship, Tomas outed him to the department. Two officers tormented him over his sexuality and when they were later fired, they gave Julien a "blanket party," seriously injuring him. He later confronted one of the officers and broke his arm in retaliation.
After the blanket party, Julien's work became sloppy and aggressive (most likely because he just had surgery on his back) and his relationship with Vanessa began to flare because of it. He was also partnered with a new officer after Danny was fired from the Barn and upon her return, he preferred to work with his new partner, enjoying the comradeship. However, his new partner was involved in a scandal, inadvertenly getting his own family killed, and was fired from the force. Since he failed getting his job back (and later killed himself in the parking lot), Aceveda paired Julien with Danny again.
During Monica Rawling's tenure as captain, Julien became more outspoken and disapproved of her seizure policy to the point that he was going to transfer out of the department, but when the policy was shut down and Rawling was dismissed, Julien decided to remain.
He soon became a training officer himself and was very tough on trainee Tina Hanlon. Due to many mistakes and Julien and Danny's recommendations, Tina was about to be dismissed until a possible scandal kept her in the Barn under the mentoring of Dutch Wagenbach.
During the formation of a new Strike Team, Captain Claudette Wyms offered Julien to Kevin Hiatt as a possible addition to the team. Claudette made the offer to Julien, who was hesitant, mainly because of the thought of being partnered with Vic on a daily basis. After being assured that Mackey was going to be moved out of the team, Julien accepted the promotion, and is now an official member of the Strike Team.