“But love and hate, he thought now, good and evil, lived side by side in the human heart, and not merely in differing proportions in one man and the next, but all good and all evil. One had merely to look for a little of either to find it all, and one had merely to scratch the surface. All things had opposites close by, every reason a decision against it, every animal and animal that destroys it…..Nothing could be without its opposite that was bound up with it…..Each was what the other had chosen to be, the cast-off self, what he thought he hated but perhaps in reality loved….there was that duality permeating nature……Two people in each person. There’s also a person exactly the opposite of you, like the unseen part of you, somewhere in the world, and he waits in ambush.
Patricia Highsmith, Strangers on a Train