James Heath was a Cortexiphan test subject.
He is responsible for the death of his sister Julie Heath, because he transferred his cancer onto her temporarily. He goes on a cancer-transfer spree and is apprehended by the FBI, who place him into a coma. ("White Tulip")
Later, he has learned how to control his ability and heal others. He is the first person to die after the group travels to the Alternate Universe, having a sudden cancer attack as the new universe renders him unable to heal. ("Over There: Part 2")