Foreman attended Columbia University as an undergraduate before matriculating to Johns Hopkins Medical School. His academic performance was impressive, as he mentioned in the pilot he had a 4.0 GPA through medical school, a fact confirmed by Dr. James Wilson in "Histories".
Little is known about Foreman's past, although it has been suggested that his family was not very well-off and his parents are currently living on a pension (cf. "Histories"). Foreman was also a former juvenile delinquent who once burgled houses and stole cars. (House claims that this was a major factor in his decision to hire Foreman, that Foreman's delinquent past makes him useful in identifying criminals.) His father, Rodney (who appears in the episodes "Euphoria, Part 2" and "House Training"), is deeply religious, while his mother is unfit to travel, due to Alzheimer's disease; Foreman also has a brother, Marcus, who is incarcerated for drugs. Although he has a somewhat strained relationship with his parents, they are both shown to love him very much despite their lack of emotions towards him. In the episode, "Heavy", he told an overweight patient that he struggled with childhood obesity until the 9th grade, although he may simply have made it up to comfort the patient.
When Michael Tritter offers Foreman an opportunity to win early parole for his drug-addicted, incarcerated brother, Marcus, Foreman turns it down. Tritter sees this as hypocrisy, citing Foreman's own criminal record, and says that while Foreman tries being compassionate to ward off House's training, he is actually just as cold and methodical as his employer. That is supported when Foreman gives his girlfriend a chance to go to a nurse practitioner school as a way to end the relationship, and she states that both he and House cannot stand to let people get close to them. He eventually gave his two weeks' notice to quit, as he was scared that he was turning apathetic towards patients' well-being—or as he admitted in the Season 3 finale, he does not want to turn into House. House angrily countered that he was like him, and in many ways was more selfish by caring about how good he looked in the eyes of patients and by dragging out his resignation until House admitted he wanted him to stay. Foreman left without a word following this tirade.
In the episode "The Right Stuff", Cuddy reveals that Foreman took a job at New York Mercy running the diagnostics department. In the episode, 97 Seconds, we see that despite a desire to change he is unable to break from House-like techniques, including using a whiteboard to brainstorm, but more importantly, disobeying the hospital administrator, believing that her idea is wrong and his idea will save the patient. The only difference is that since House is a known brilliant doctor, he has earned the trust that Foreman has not yet earned. So despite the fact that Foreman's idea is right, his boss states that Foreman had no way of proving that his idea was the correct one, and if she cannot trust Foreman to obey her, he cannot stay at the hospital. She then fires him.
Cuddy then offers Foreman his old job at Princeton-Plainsboro, claiming she needs someone to help control House. At first he declines the offer, but ultimately he accepts following an extensive series of failed job interviews. He finds that his insubordination at New York Mercy has led the medical community to conclude that House has trained him to be a loose cannon with no regard for authority or procedure... a "House Lite," as Dr. Cuddy describes him.
He rejoins the department in the episode "Mirror Mirror", serving as Cuddy's eyes and ears on House's new team. Though House tries to make Foreman miserable enough to quit, Foreman soon realizes that the unorthodox and rapidly changing environment of House's diagnostics team is exactly where he wants to be, and the two return to speaking terms. Though House and Foreman are more confrontational than before due to Foreman's role as a buffer for House, House clearly still respects his skills, as is evidenced in "Whatever It Takes" when he chastises his fellows for not listening to him.
Like House, Foreman has also been shown to be extremely honest even at the cost of hurting other people's feelings. This is evident in the episode "Sleeping Dogs Lie", in which he tells Cameron that the two of them were never friends, merely working colleagues. However, during a later bout with a deadly illness (see below), Foreman recants this position. His sincerity, given his dying state, was unclear, and she initially refused his apology, but accepted when he was placed in a chemically induced coma. Similarly, in the episode "Resignation", he tells Chase that he's never liked him and never will.
During Season Three, a change in Foreman's character, making him more sensitive to other people's feelings, can be noticed when he resists telling two interracial lovers that they are half-siblings. During the same episode, he is accused of being against interracial relationships. Foreman makes a bet with House saying that Dr. James Wilson is not dating a nurse in the hospital. The white nurse is actually dating Foreman, which explains his sensitivity to this particular case. Later, Foreman offers a Romani boy an interview for the intern job and tries to help him.
The season three episode "House Training" reveals a great deal about Foreman's character. Upon giving orders for a patient to be given immunosuppressing radiation treatment and then learning that it was nothing more than a staph infection (the radiation therapy killed the patient's immune system, essentially dooming her to a painful death), he is visibly agonized and blames himself for killing her. Throughout the episode Foreman displays a passionately emotional side and at one point breaks down, stating that in many ways he is no better than from where he came simply because his ego has gotten in the way. In the following episode, Foreman is seen for the first time praying or meditating in the hospital chapel, despite the fact that he has expressed being fairly nonreligious before.
Foreman was able to get over the grief and trauma of killing a patient, and the self-doubt that his mistake caused, when he was able to save another patient's life by taking extreme measures. With a young boy dying unless he got a bone marrow transplant immediately, Foreman was forced to get the marrow from the patient's little brother, without anesthetizing the boy first as he was too sick to be sedated. Foreman strapped the boy down to a bed and drew the marrow from him by force in several places on his body to get the samples he needed, ignoring the boy's screams of agony in order to do so. The patient survived as a result, and while Foreman acknowledged this, he was also horrified with what he had done. He tendered his resignation the same day.
Foreman takes a job at Mercy Hospital in New York, and he immediately goes out of his way to conduct differential diagnoses with a calm head and professional attitude, almost the exact opposite of House. However, when a patient presents with a condition with similar symptoms to the patient he killed, Foreman goes against regulations (like House) to save the patient's life, which he does. Despite making a life-saving call, Foreman's administrator fires him due to violating regulations. Foreman is then re-hired by Dr. Lisa Cuddy to serve as a partner of sorts with Dr. House and to act as the "eyes and ears" of Dr. Cuddy on House's team. His position is permanent, as he cannot be hired anywhere else. His personality appears to have changed drastically since being re-hired and has become distinctly sarcastic and biting, and although he shows some level of restraint, his sense of humor has become very similar to that of Dr. House. He nevertheless states that he does enjoy being back at PPTH and working with House again.
Significantly, Foreman has picked up House's habit of practicing medicine in plain clothes, eschewing the white coat he wore during his first hitch as a member of House's team. However, his outfit is still more professional than House's, tending toward well-tailored suits and ties.
Foreman is a fan of jazz music, first shown in the episode "Who's Your Daddy?" when Foreman makes a Miles Davis reference, and later in the episode Insensitive where he plans to attend a jazz festival.
Although House stated in the pilot that he hired Foreman because he was an ex-car thief, House often states or implies that he thinks Foreman is a great doctor. The best example of this is in the Season 2 Episode "Autopsy". House and the surgical team are trying to determine the exact location of a blood clot in order to be able to remove it. Foreman swears he spotted a clot on the screen that neither House nor anybody else saw. House nods his head and states "That's good enough for me." Also, in the third season finale "Human Error", when House is trying to stop Foreman's leaving, he bluntly declares that he is "indispensable" and that "he needs him" on his team, in an unusual display of respect for a subordinate.
Since Foreman's return to Princeton-Plainsboro Hospital, it has been shown that House still holds a deep level of respect for Foreman. In stark contrast to previous seasons, he tends to treat Foreman as an equal in his understanding of diagnostics and Foreman in return shows a marked regret at having quit the job in the first place. In "Whatever It Takes", House lectures his new fellowship candidates when they fail to listen to Foreman's instructions while House is away. House asks the team who he put in charge. When they answer "Foreman", House tells the candidates that the reason he left Foreman in charge was because Foreman knows what he's doing and to listen to him next time.