You sense a pure soul at the door and you quickly move to trap whomever enters. You grab your girlfriend by the scruff of the neck, her body still trembling with orgasmic aftershocks and no doubt succumbing to the perverse thoughts you sense strongly within her, and wait behind the door.
When the person enters you immediately recognise your roommate. Your mind conjures several images of gay sex, before now a repulsive concept, and you are filled with the determination to carry out your evil plan.
With one swift kick the door is shut. He turns and you grab his head, shoving his face into your girlfriend's cum-soaked cleavage, and watch with building arousal as a tent forms in his trousers despite his pitiful struggles to get away.
You let go of your girlfriend who collapses to the floor in frenzied masturbation. She is eagerly shoving all traces of your corruptive seed with her free hand and from the way the seams of her trousers are splitting you know that her transformation is in its final stage. As much as you want to watch her leave her humanity behind however, you have more pressing matters to attend.