Omegaverse (also called A/B/O) is a fictional worldbuilding trope that adds a secondary biological and social system to humans or humanoid characters. Individuals are typically classified as Alphas, Betas, or Omegas, each with distinct biological traits, instincts, and social roles. Common features include scent-based communication, pheromones, mating cycles (such as heats and ruts), pair bonds, scent marking, and varying reproductive systems depending on the setting. The exact rules differ between works, but the trope generally explores how these secondary dynamics influence society, relationships, hierarchy, identity, and conflict. Omegaverse is not a real biological system; it is a speculative fiction framework used across fanfiction and original fiction, and stories may range from action and politics to romance or psychological drama.