This is a story of a young woman who faces the challenges of growing up with a brother whose mental disorder presents as menacing, violent and angry. Both her life and her parents’ lives have been centered on his maintenance and on avoiding confrontations that would hurl him into one of his “Moments!” Despite extreme vigilance on the part of the parents, and despite the monumental costs of failed treatments, the young man does the unthinkable. He kills innocent children and teachers. However, this is not the story of his atrocity, but rather of the aftermath of his behavior on his sibling. The focus of the story should not be construed to mean that the plight of the victims and their families is being minimized in the account. This is definitely not the case. However, little has been written about how the lives of the siblings of mass murders were/are affected. “The Lynx and the Lioness” offers a glimpse into what has happened to some of these siblings through no fault of their own. While it is only the story of one sister, at the same time it contains the stories of many siblings thrust into this situation. It tells the tale of how simply being born into a family with a brother or sister who is volatile, and who has not been or perhaps cannot be helped by modern psychiatry and/or psychology, had profound influences on the life of a sibling: some influences good and some devastating. This story contains elements, though unidentifiable, from interviews and assessments that the author conducted on the families of murderers and on the families living with aggressive and unpredictable offspring. It is not a true story but contains experiences that were common to many. It certainly argues for better prevention, better mental health facilities, follow-up, and if needed, constant care and supervision for those who suffer and cannot be integrated safely into society.