Newly presented Alpha Yuji being shown how to knot by alpha kuna as kuna picks an omega that he can kill after Yuji fucks them. Kuna is repulsed by omegas and was happy Yuji presented as an alpha which doesn’t mean they’re not mates, it just makes it harder to be around each other without omega pheromones tempering their aggression in a rut. You can’t bitch alphas who have cursed energy in this au, and Yuji and kuna have been in an arranged marriage and mating since they were born, and everyone including Yuji was upset that him presenting as an alpha would call it off, but sukuna was like no wait babe I got this.

Yuji or kuna uses the omega, knotting them over and over until their rut is done and then the other rips their throat out with their teeth, because rut instincts to breed keep the possessive-territorial instincts at bay so once the rut clears they’re incredibly how fucking dare you touch my mate bloodthirsty. Also since they’re mates, their ruts sync up, so they share the omega, using them as a glorified sex toy, their instincts wanting to breed the omega like they’re competing for the womb.

Outside of rut, they have no issue with switching/bottoming.