Cain absolutely dreaded them, whether they were considered monsters, demons, or devils, it didn't matter. Normal people could hold to the hope of fighting one of the same genders, a male adventurer would prefer to fight an incubus for example. Cain on the other hand knew the truth, Cubuses are gender-less, they simply take the opposite gender of their target. If a Cubus was fighting a woman, it will appear as an incubus, if it was a man then a succubus.
Cain's team contained three women and he was the only male, the possibility of the Cubus appearing as an incubus is very high. That was bad news as the girls simply don't have what it takes to resist a 20 charisma.
He might be able to keep Alice safe by controlling her directly but the other two just can't resist. The moment the Incubus appears, those two will go into heat instantly.
The Cubuses freely control their gender to gain an advantage in battle, this is going to go badly, and Cain could feel it in his bones.
