supports the feelings of her younger sister, Anna, and is thankful for the bodily donations Anna has been made to give her throughout her lifetime. At the end of the novel, Kate is revealed to be the one who asked Anna to sue for medical emancipation, because, fed up with the awareness of how much she took from her and the rest of their family, she wanted, for once, to be the sister who protected the other one. Andromeda "Anna" Fitzgerald - A girl who was biologically engineered in order to be a "savior sibling" to her elder sister, Kate. At first Anna was only meant to donate her umbilical cord, but in response to Kate's relapses, Anna repeatedly donates blood, marrow, and eventually, an organ to her. She is thirteen years old at the time the novel takes place, and seeks to be medically emancipated from her parents. She believes that this legal support is necessary to help her resist the growing pressure on her to donate a kidney. She is the main protagonist of the novel. Jesse Fitzgerald - The oldest Fitzgerald child. Throughout most of the novel, he is a delinquent teenager, but eventually reforms after a confrontation with his father. Sara Fitzgerald - The controlling mother of Kate, Anna, and Jesse. She tries her hardest to keep her oldest, ill, daughter alive and well. Sara refuses to accept the idea that Kate is likely to die, and in doing so she neglects the needs of her two other children, whom she keeps seeing in relation to Kate. Before the novel's end, Sara finally listens to Anna about Kate and comes to terms with Kate's choice to die, expressing remorse for her behavior. Brian Fitzgerald - Sara's husband, who understands Anna's decision to not donate her kidney, but also feels compassion for his wife. He is fond of astronomy and becomes torn between his daughters, and his wife, during Anna's emancipation trial. Ultimately, Brian sides with his wife during his testimony in court, regardless of his conflicting feelings. He also shows concern for his son, and is the one to confront him about his troubling behavior. After Anna's death, he too needs a lot of time to cope with it. Julia Romano - The court-appointed, guardian ad litem, whose job it is to decide what is best for Anna. She also often advises Anna regarding medical emancipation.