In the first episode, Billy approached Alison Parker in response to her search for a new roommate at Melrose Place. Alison was initially reluctant, and the two got off to a comically negative start. When Alison was unable to find a more compatible match, however, she tracked Billy down and politely took him up on the offer. Billy later came to Alison's aid one night when he found a man from her job making unwelcome advances in their living room. He peacefully drove the man away while posing as Alison's husband, which brought the two new roommates closer.
More than friendsAlison grew uncomfortable when Billy started dating Amanda Woodward, an executive at her job who she worked closely with. In time, the resentment between the two women drove Billy and Amanda apart. Though initially an aspiring novelist, Billy went to work for a magazine as a staff writer. He was the object of sexual harassment by his boss, Nancy Donner and had a love-hate relationship with co-worker Celia Morales. Later, he found his calling in advertising, and began working alongside Alison and Amanda at the D&D agency. Billy was comforted by several of his friends, including Amanda, following the death of his father. In time, he and Alison began dating. Shortly afterward, though, Amanda revealed that she was pregnant with Billy's child. However, she later miscarried.
Billy and Alison eventually separated as their relationship became rocky, with Billy leaving for a job promotion in New York. As the two began to miss one another, Alison soon paid him a brief romantic visit. Billy later returned to L.A. and surprised her by proposing. Though Alison initially accepted, she later fled the wedding due to the sudden arrival of a personal issue from her past. Billy eventually reunited with Alison at her sister's house, chasing off their abusive father. After Alison later declined to elope with him, citing her unfinished personal business, their romantic relationship would enter an on-again, off-again period in the times to come.
Billy eventually became involved with the wealthy and brash Brooke Armstrong, who manipulated him into thinking that Alison was no longer interested. After marrying Brooke, Billy became annoyed by her occasionally pompous father Hayley. He was eventually prompted to move back to Melrose Place, where he lived alone until Brooke followed him and expressed her devotion. However, the couple's differences still led to a natural friction between them. In time, Billy and Brooke came to believe that they were expecting a child. After Brooke discovered that this was actually not the case, she chose to keep this knowledge hidden from her husband.
Upon discovering the truth on his own, an outraged Billy declared that the marriage was over. He later changed his mind after feeling sympathy for Brooke as she recovered from injury. Soon afterwards, however, Brooke's actions pushed Billy away once again. After a drunken Brooke accidentally killed herself, a guilt-ridden Billy briefly saw visions of her. For a time, he also took on the colder aspects of her personality. Once Billy came to realize what he was becoming, he returned to his regular self, visited Brooke's grave, and said a final goodbye. Billy later fell in love with and eventually married Samantha Reilly. However, their unfaithful ways weakened the marriage, and the two eventually divorced.
Billy was the last of Alison's friends to say goodbye as she left town. The two hugged, kissed, and shared an affectionate farewell, acknowledging their longtime bond and their status as close friends. Billy later began dating and fell in love with Jennifer Mancini. In their respective final episode of the series, Jennifer accepted Billy's offer to move to Rome with him.