An omega-dominant omegaverse.

Has omegas, alphas, betas. Only omegas can carry pregnancies; only alphas can impregnate.

Central feature of verse is that for [biology or something technobabble] reasons, making pregnancy-capable people is very hard. Omegas run about 1 in 5; everyone else has ended up with strong instincts about listening to them (and protection).

Being in charge of things is the exclusive provenance of omegas.