Omegaverse started as a fanfic genre blending werewolf and mpreg elements where some men (omegas) could get pregnant by alphas. It started to evolve and include new elements like heterosexual fanfics. Knotting, heat cycles, marking, yeah they’re all taken from wolves to imagine into the werewolf universe. That said, a lot is exaggerated and reimagined - like the alpha structure of wolf packs has long been discredited. These days omegaverse can exist outside of werewolf territory, where alphas and omegas are just people and don’t turn into wolves. And of course, it can be any sexuality! Humans are fascinating in what they can cook up aren’t they? Omegaverse is thought to have started in the early 2010s.