Spiders are Pragmatists, Prey/Predator dynamic requires context, spiders hide/flee from superior predators, a demonstration proving you are higher on the food chain would inspire her to submit in favour of continued survival for herself and her offspringVenomina
Venomina is a spider & spiders eat their mates. MC has no power in this dynamic as he must keep her well fed & satisfied in order to have sex. Anyone who thinks she is sub dosent understand the power dynamic that's at play: This is prey fucking a predator...
Erevi on the other hand is a true Dom, I imagine her Ego might force her to fight to the death rather than submit, the only way I can imagine Dominating her would be with the support of her god. (or her daughter)