Arthur is Dominick Cobb's right-hand man. Although Cobb is the master planner, Arthur takes care of the details, does the research, and makes sure everything is right. Sharing dreams is not just a job for him; he finds his work fascinating.
Arthur is Cobb's right hand man, and apparently closest friend. They have known each other since before the tragic death of Cobb's wife. He lives in America, but travels the world with Cobb. Arthur and Cobb used to work with Eames, but Arthur and Eames appear to dislike each other now. The three never divulge any information about their past experiences together so no further facts can be drawn.