Parasitic Predatory Possession

Brenda is a mousey introverted woman recently divorced from a man she despised. After what Brenda thought would be a quiet night of celebration, she wakes the next morning in her bed, hung over, a horrible taste in her mouth and extremely sore in at least two of her orifices. A call on her cell from an unknown number fills her in on what happened to her the night before. And learns she has been possessed by an intergalactic alien, that uses her in a parasitic fashion to sustain its existence.
The alien explains that their relationship at first will be completely parasitic, but in time that will evolve into a more symbiotic one. To accomplish the aliens goals, the alien communicated mentally with Brenda, and begins grooming her for its own purposes. The self-serving purpose of having Brenda engage in lesbian activities. The product of Brenda's activities, is the nourishment that sustains the alien.
And the alien is ravenously hungry.