In the book the relationship with Katharine and Almasy is sort of only in the patient's mind.
Great artistic talent in any direction... is hardly inherent to the man. It comes and goes; it is often possessed only for a short phase in his life; it hardly ever colors his character as a whole and has nothing to do with the moral and intellectual stuff of the mind and soul. Many great artists, perhaps most great artists, have been poor fellows indeed, whom to know was to despise.
According to legend, one day a man was wandering in the desert when he met Fear and Plague. They said they were on their way to a large city where they were going to kill 10,000 people. The man asked Plague if he was going to do all the work. Plague smiled and said, No, I'll only take care of a few hundred. I'll let my friend Fear do the rest.