Omegaverse

Omegaverse, also called A/B/O fiction, is a subgenre of speculative erotic fiction built around an invented human dominance hierarchy modeled loosely on popular ideas about wolf pack structure. Characters carry a secondary sex on top of their ordinary one, split into commanding alphas, ordinary betas and submissive omegas, and the genre layers animal-derived traits onto its human characters, including heat cycles, scent marking and mating behavior, with male omegas typically able to become pregnant. The genre began in 2010 inside fan fiction written for the television series Supernatural, combining existing werewolf fan fiction with an established male-pregnancy fan fiction tradition, and the name Omegaverse itself was in standard use by mid-2011. It spread rapidly across other fandoms after that, and by the later 2010s had moved beyond fan fiction into commercially published romance and erotica.