About ten years before the start of the series, House and Stacy met at a doctors vs. lawyers paintball tournament when she managed to shoot House and put him out of the game. She revealed to Cameron that their first date went horribly and she never wanted to see him again. However, next week, she moved into his house.
Five years later, Stacy was still House's live-in girlfriend when he was diagnosed with the infarction in his leg. House had decided to undergo a very risky procedure which required that he be put into a coma. However, when he was in the coma, Stacy used her power as medical proxy to decide to remove the dead muscle tissue instead. Although this procedure probably saved House's life, it left him chronic pain and permanent weakness in his right leg. Afterwards he seemed to resent her for not trusting his judgment and she took up smoking.
House's relationship with Stacy continued after his disability started, and even House admits she was very supportive about his disability. However, House remained bitter about Stacy's overruling his medical judgment, frequently confronting her on it. This put too much of a strain on the relationship and Stacy eventually left.
Five years after their break up, Stacy had married a man named Mark Warner. House finally diagnosed him with acute intermittent porphyria, which most likely saved his life. However, Mark's illness required a lengthy period of convalescence. Because Cuddy needed a lawyer for the hospital, she offered Stacy the position so that she could help care for Mark. However, both Cuddy and Stacy agreed that House had to agree with the arrangement and, after Cuddy asked, he did agree, but not with any enthusiasm.
Their new professional relationship started poorly. House lied to her about getting Cuddy's consent to bring a patient on death row to the hospital. Afterwards, she asked him if she could trust him. He told her that the patient would have died if he hadn't lied to her. He confided to her that after he had cured the patient he was keeping him in the hospital because he thought he was still sick. He told her not to tell Cuddy but she did.
Later, House stole her therapy file and learned that she wasn't sleeping with Mark. He came to her house, ostendibly to get legal advice after he was accused of striking a potential patient, and helped her wash the dishes. After learning that she had a rat in her house, he decided to get rid of it as an excuse to spend time together. They grew closer together and nearly kissed, but it all fell apart when she realized that he had stolen her file and was using the information from it to manipulate her.
When they were stuck in a hotel in Baltimore together they shared a kiss, but further advances were ended when his team called him about a case they couldn't handle themselves.
Wilson talked to Stacy about her increasing closeness to House. He told House that she seemed confused but he didn't think she was; she was waiting for him to do something. They ended up having a one night stand. She decided that she was going to leave Mark. But then House realized he didn't really want to destroy Mark & Stacy's marriage, prompting him to end his relationship with her. Stacy quit her position, and she and Mark moved out of the house where they had been residing.
Housy is also known as Hacy.