Novelist Sally Hepworth says a key inspiration for The Good Sister was the play between her two young daughters. The children would be hugging one moment and physically attacking each other the next. When Hepworth scolded the younger girl for biting her older sister, the older girl asked her to leave her baby sister alone, as she loved her. “If there isn’t a book in that kind of relationship, I thought, my name isn’t Sally Hepworth.” The Good Sister takes the idea of the fascinating, complex relationship between sisters and adds another dimension to it by making one of the sisters a little too manipulative for comfort. Though Rose is the obvious villain of the piece, Fern continues to feel a pull toward her. It is difficult for Fern to say with surety that she and Rose do not love each other despite everything that has transpired between them. In a twisted way, the reason Rose feels she can do whatever she wants where Fern is concerned is because she doesn’t feel separation from her. As Wally astutely notes, Rose often behaves as if Fern is her possession or an extension of her ego. If Fern is Rose, or the more inferior part of Rose (as Rose sees it), Rose has the discretion to punish this part.