Dr. Allison Cameron is an immunologist that was hired to House's team six months prior to the pilot episode. House explicitly informed her that he hired her based on her looks because he believed that a pretty girl who went into medicine shows greater dedication compared to an ordinary-looking student because the former could have easily used her looks to get an easier job. Prior to working at PPTH, Cameron was a medical intern at the Mayo Clinic, and was one of the top students in her class in medical school. She hails from the Midwestern United States and that has a sibling, an unnamed older brother. Cameron is known for her honesty, sincerity, idealism and possesses a strong moral and ethical center. She is hyperopic and an atheist. Markedly flawed, she has complex relationships with her colleagues; not least of all with House, with whom she had admitted to have been in love with. Cameron is occasionally hesistant and unwilling to perform House's bidding when she is required to deceive their patients and has gone to head-to-head with him before several times on the issue. In one episode, Cameron even disagrees with House about the best kind of cheese, maintaining that goat cheese is preferable. She has also shown extreme reluctance to deliver bad news to patients or their families. Despite this, she has been effective in gaining patients' trust and approval of diagnostic procedures when the need arises, in contrast to House's strong-arm methods.
The character underwent a growth in development when she proved to be far more assertive in her beliefs and actions in season three showing that she was not above employing tactics used by House in order to get the job done. However, her consistently good intentions did not change and her loyalty to her boss was proved unquestionable as evidenced by his legal troubles -- being previously under investigation for alleged drug addiction and trafficking. Her allegiance came to an abrupt end, however, when she surprisingly resigned in the season three finale.
Her awkwardness with death was explained when she confided in House that she had once fallen in love and married when she was 21. However, the marriage lasted only six months ending with her husband's death due to thyroid cancer that had metastasized to his brain. She also revealed to Dr. James Wilson that she had met her husband shortly after he was diagnosed and that if they hadn't married, he would have died alone. Cameron was invited to move to Africa by Dr. Sebastian Charles, a world-renowned activist, a fellow immunologist and patient, and then later, on a date. She confided in Dr. Chase who expressed his doubt that she would go out with Dr. Charles despite their mutual attraction, simply because he wasn't House. At the end of the episode, she declined both offers. In "Hunting", a HIV-positive patient accidentally coughed blood into Cameron's mouth and eyes, putting her at risk of contracting the disease. In order to make her take her final HIV test months later, House told her he loved her out of the blue; her mouth dropped open in shock and House quickly swabbed the inside of her cheek. Cameron later learned that House had opened her test results before she had a chance to find out herself, justifying his actions by citing the letter's confidentiality and that he had simply wanted to know.
Cameron's friendship with Dr. Foreman became strained after she accused him of plagiarizing her article for a medical journal after his was published. Her frustration and anger were further exacerbated by her peers' indifference. She eventually confronted Foreman and apologized for the way she had treated him, claiming she didn't want to damage their friendship only for her colleague to say they were never friends in the first place.
In the third season finale, Cameron became the lone fellow of the Department of Diagnostic Medicine after her colleagues, Dr. Chase and Dr. Foreman, were fired and resigned from their posts respectively. She bid farewell separately to the both of them, even giving the latter a framed citation of his published article in reference to their previous conflict the year before. In the episode The Right Stuff, Wilson claims that she is engaged to Chase and living in Arizona after House believes he is having visions of her in the hospital. It is later revealed that he was lying to House -Cameron now works in the ER (with now blond hair) and she is dating Chase. The two got engaged in "Saviors" when Chase proposed to her in the hospital's locker room after a very brief break up. They got married in the season 5 finale but in "Teamwork" Cameron left Chase, quit her job at PPTH and moved back to Chicago after Chase admitted to murdering a patient. In episode 8x20, we learn that she is the Head of Emergency Medicine at a Chicago hospital.