Lucas Douglas was the private investigator House hired in season 5 of House M.D.
Lucas, played by Michael Weston, first becomes involved when House asks him to investigate people and situations outside the hospital. His unusual occupation and willingness to pursue ethically questionable assignments make him a useful, if unpredictable, extension of House’s investigative habits.
The character is introduced during the fifth season and becomes part of several personal and professional storylines. House uses Lucas to gather information about colleagues, romantic interests, and other people connected to the hospital. Lucas later develops a closer relationship with Cuddy, creating additional tension in House’s already complicated personal life.
The name is easy to confuse with Michael Tritter, a police detective whose season 3 conflict with House forms a separate major storyline. Tritter is not House’s investigator. Lucas Douglas is the private investigator, and Michael Weston is the actor who portrays him.