This article argues that Roxana exemplifies a peculiarly modern mode of “derivatization”: a form of “ontological reductionism” articulated by Ann J. Cahill in which individuals are diminished to “the reflection, projection, or expression of another being’s identity, drives, fears [...] reducible in all ways to the derivatizing subject’s existence”. The essay analyses the novel’s representation of secondary characters’ stunted subjectivities and the protagonist’s exploitation of their body, agency, and consent. Reading the sexual assault on Amy as an example of Roxana’s pleasure in overriding subjective autonomy and a violent expression of her “separated capacity”, the article shows how the novel explores the social and subjective self-harm of such instrumental approaches. The article suggests that not only does derivatization characterize all of Roxana’s relations, including those with men, but that its ethical harms are also the ultimate cause of her tragically reduced selfhood.