maybe reward and punish the player
my thought is maybe the monster can smell our girls pussy juices so as she uses her body he can slowly track her over time
having things like a sex suit that increases her speed
or a shop that breeds her
or a alert system that when you set it up it sets off a siren to lure the monster but in turn it requires her to fill up a tank as it also sprays a girls lust in that area
sorta a risk reward system