Lucas Douglas is a private investigator hired by House in Season 5 to keep track of Wilson. He is portrayed by actor Michael Weston.
At first glance, Lucas seems ill suited to be a private investigator. He cannot effectively disguise himself and can easily be spotted as an impostor in many situations. He cannot follow people without being spotted. He cannot pick appropriate places for carrying out surveillance.
However, it was soon obvious that these weaknesses often made people underestimate him. He is capable of great feats of deduction, very little escapes his attention, he can gather information quickly when given a chance, he finds out the most interesting facts about everyone, and he is almost always right about his conclusions about people. He correctly surmised that House wanted him to keep an eye on Wilson before House even mentioned his name.
He soon took a liking to Cuddy and has attempted to start a relationship with her. However, he also quickly surmised that, despite House's protests and denials to the contrary, that House was also romantically interested in Cuddy. He has challenged House to see "who gets there first".