well my thought is making the aggressive mc a amazon futa could let her do stuff like pinning fullnelson and mating presses
while the main mc could be more kind and caring
another idea could be to add mixed gender monsters 1 thing you could do is demons sucubi and incubi
another thought is abilitys if you could use a grab mechanic with the aggressive mc you could use pin this would give you the ability to use a ability called breed the more brutal mc could be more about hardcore breeding and butchering enemys
where you could get a ability called pounce for the main mc this lets her pin people and monsters down with her own weight
if you made a apart of the lore that all the creatures prefer breeding as their all horny you could also give the enemys a primary attempt to breed where they can use pounce or pin against us giving the mc a primary ability to break free could be smart as well as this lets players who want to be pinned to get pinned
another idea could be a 3rd mc who is more about tech and crafting
if 1 is lust and 1 is aggression maybe nuteral is a crafter she wears a work belt and has a cyber tail her sex stuff could be based on using tech like her tail to hold mates in place by their necks as she study's enemys
this could even go into a new research menu that gives you buffs to each enemy like giving the domination mc buffs to breeding damage or giving the main mc the ability to charm enemys thru sex
to keep in the research mode maybe have a option where the mc form changes dynamicly but you can choose to perma set it
like it currently is giving the mechanic a 10-15% range in the middle could be nice