When two humans have lived together for many years it usually happens that each has tones of voice and expressions of face which are almost unendurably irritating to the other. Work on that. Bring fully into the consciousness of your patient that particular lift of his mother's eyebrows which he learned to dislike in the nursery, and let him think how much he dislikes it. Let him assume that she knows how annoying it is and does it to annoy - if you know your job he will not notice the immense improbability of the assumption. And, of course, never let him suspect that he has tones and looks which similarly annoy her. As he cannot see or hear himself, this easily managed.
C.S. Lewis, The Screwtape Letters
charity, compassion