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 offspring (no different from how she submitted to Erevi)Venomina
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)