He's made it clear that he does not believe the interaction between the two dimensions is good and suggests they should build a wall and forget it.
Ian Shaw is portrayed by Nicholas Pinnock.
He travels to Dimension One with Emily to investigate the events surrounding Baldwin's capture by German Police. (See The Lost Art of Diplomacy)
Ian rushes to the hospital to see Emily and confronts D1 Howard. (See: Both Sides Now)
Ian questions D1 Howard with a lie detector. Emily lets him into their investigation of the Potsdam house. (See Act Like You've Been Here Before)
Ian takes out one of Pope's men before he can kill Kasper. Together with D2 Emily, he questions the lie exam man. (See No Man's Land (Part One))