Detective Nathan West arrived in Port Charles determined to solve a twenty year old police case. He procured a position at the Port Charles Police Department from Anna Devane and evaded the commissioner's questions regarding his decision to leave the New York City police force. Nathan agreed to partner with Dante Falconeri but requested permission to follow up on a cold case in addition to his regular duties. Nathan believed that several years ago Silas Clay had injected his wife Nina with an overdose of an anti-depressant which led to her comatose state and later her death. Although the case was over twenty years old, Nathan was determined to find justice for Nina.
Nathan spoke often of his disgust for Silas and admonished him for engaging in an affair with Ava Jerome while he was married to Nina. Silas admitted that he had been involved with Ava years ago but insisted that he did not bring harm to his wife. As Nathan continued to investigate the case, his personal connection to Nina was revealed when Nina's mother Madeline arrived in Port Charles. She paid her son Nathan a visit and he explained that his plan to seek justice for his older sister Nina was underway. He assured his mother that Silas had not recognized him as Nina's younger brother and that no one in town knew that his real name was James Nathan Reeves.
Although Nathan was sure Silas had harmed his sister, he agreed to entertain the possibility that perhaps Ava had committed the crime. Nathan set a trap for Ava but was caught his mother instead. She confessed that she had harmed Nina in an attempt to protect her from Silas after Nina realized that she was pregnant. After Nathan arrested Madeline, he spent a night discussing his family drama with Britt Westbourne. The next day, Nathan was dealt another blow by Madeline when she warned him not to become romantically involved with Britt because she was his sister. She explained that her younger sister, Liesl Obrecht, had given birth to him.
As Nathan processed the truth about his family, Madeline informed him that Nina was alive. Although he was hesitant to believe his aunt, he was overjoyed when he learned that Nina was in Port Charles and staying with Silas. Nathan paid his sister a visit and explained that although they were technically cousins, he would always view her as his sibling. Meanwhile, Nathan befriended his roommate Maxie Jones. Maxie's boyfriend Levi disapproved of their friendship but Nathan continued to spend time with her and encouraged Maxie to be a part of her daughter's life. Nathan was by Maxie's side when she asked the judge to reconsider her custody petition and he lied to the judge in order to strengthen Maxie's case.
Nathan's plan to help Maxie backfired when the judge received an anonymous tip that Nathan had lied under oath and she was denied custody. Levi blamed Nathan for Maxie's continued separation from her daughter although Maxie did not agree. Maxie and Nathan continued their friendship until Levi accused Nathan of reporting his illegal immigration status. Nathan denied contacting immigration but Maxie kicked him out of the apartment and announced that Levi planned to remain in the country as her husband.
As news of Maxie's engagement spread, Nathan realized that he had romantic feelings for her. On the day of her wedding, Nathan learned that Levi was a con man and confronted him. However, Levi gained the upper hand when he assaulted Nathan and tied him up. When Dante freed Nathan, they raced to stop the wedding and revealed the truth about the groom. Levi admitted that he was a jewel thief and that Maxie had been a means to her mother's Aztec jewelry. He took Maxie hostage at gunpoint while his accomplice, the man that had pretended to be an immigration agent, grabbed Dante's wife Lulu. Levi shot Mac in the chest as he and his partner in crime escaped with Maxie and Lulu.