This article proposes a comparative reading of human-animal interaction in C. J. Cela’s The Family of Pascual Duarte and M. L. Rijneveld’s The Discomfort of Evening, through the lens of the medical humanities. Drawing on psychiatry and on H. S. Sullivan’s interpersonal understanding of personality disorders, I show that the two storyworlds function as models for the real-world social reach and distribution of individual psychopathology. Affecting both children and animals, some of the traits of the cluster B personality disorders (disregard for others; lack of empathy; sadism) become embedded into the chronotope and shape the interactions between characters. These cognitively realistic illustrations of mental illness highlight the world-modelling capacity of literary fiction. They model the social impact of psychopathology, while inviting literary theory to build interdisciplinary bridges for the assessment of the relationship between fiction and reality through the prism of mental health.