I am not sure if this is an SOL story or on another site. Protagonist is a part of a family; he is in high school or college. The family members are: stepmom, oldest stepsister, protagonist, younger stepsister, youngest sister. The protagonist spikes all of the milk in the house with some sort of mind control or aphrodisiac drug and ultimately over time winds up dominating the entire family. Youngest sister winds up dominating her next oldest sister and a friend in lesbian relationships.
