Around 1800, the idea of sibling relationships coalesced to form a network of social, symbolic, and imaginary relations. We can read this fraternal structuring of the world in the literature of the period. The present study examines the meaning of sibling relationships in a broader discussion of cultural history and with a meticulous new reading of the novels of Jean Paul along with other canonical texts (Jacobi, Goethe, Schiller, Novalis). The demonstration of how a dispositif related to siblings developed around 1800 uncovers a previously hidden social dynamic, offering the basis for a perspectival shift in the cultural history of social relationships.