another idea could be injured pet you get 1 turn while under 10% hp then depending on her form depends on how she treats you
both are sexual but in her none primal mode she acts more like a mother trying to heal your wounds while she fucks incy
her motherly side could be a reverse of her primal form she might give you speed and strength but lower your breeding abilitys
but her primal form will be just that she takes you thinking your weak lossing in her primal form will grant you two debuffs while also healing your hp you gain weakness because youd be sore after her breeding you so brutally but you also get slow because thy balls now hurt like hell
while her primal version might enhance your breeding abilitys this could grant you either a buff or debuff
bloated balls for the primal side
emptyed balls for the mother side
using bloated balls might give a hidden screen for other girls but using empty balls might make you have negitives with the other girls
you could even give the sucubi the ability to refill incys ball sack by using their tails to help him out if you gain their favor