Agent Harris was initially assigned to track, and if possible keep in line, Michael Westen, through Sam Axe. He controlled him by tying up his pension, thus strong-arming Sam into providing intel on Michael, his movements, and his activities. Constantly thwarted by Michael, he eventually turns up the pressure on Sam, but Michael rescues Sam by providing him the location of a rogue Czech hitman, in Miami to kill Michael. This, along with Sam turning over some level documents Michael got his hands on, not only clears Sam, but ends his assignment of watching Michael.

Later on, Michael and his crew develop an almost friendly relationship with Agent Harris, as in multiple instances through seasons two to four, the FBI agent works with Michael, usually to achieve noble ends both sides want done despite his habit of vocalizing his wish to arrest him.