Psychoanalysis has shown that the death of a sibling is likely to have a long-standing impact on the character development of a surviving child. Among common adult manifestations are the identification with the deceased sibling, repetitive self-punitive behaviors, and the development of masochistic trends. In treatment, these patients can become entrenched in a negative therapeutic reaction that compromises the outcome of their analysis. In this paper, the author discusses the analysis of a woman with a history of losses that included the loss of a sibling at an early age. A critical part of the treatment focused on helping this patient overcome a negative therapeutic reaction that emerged as she became aware of hostile and vengeful fantasies, not only as they related to her deceased brother but, more importantly, as they related to her parents.