He returns in the fourth season as a member of Princeton-Plainsboro's surgical staff.
In the sixth season, he returns to the diagnostic team, first working for Eric Foreman, then for House when House returns to head the team after his medical license is reinstated. His father was Rowan Chase, who later became a wealthy and world renowned rheumatologist.
When Chase's father left the family, 15 year old Chase was forced to care for his mother until her death which is approximately ten years before Season 1.
He has been on the diagnostic team with House longer than either of other two members at the time.In the episode Control, Chase makes a stupid, but luckily harmless mistake.When assigned to do an angiogram on the patient, he lets the radiology resident scan the wrong leg.He also commented that she "ended up drinking half her life away and hating me," but he did call her at the end of the episode.However, Chase had a rough relationship with both his absent father and alcoholic mother.Fearing for his job when House hits the roof over the mistake, and suspicious when House doesn’t gloat after diagnosing the patient, he finds evidence that House may have known about a condition that would have disqualified his patient from a life saving transplant and brings it to the new chairman of the board, Edward Vogler.