The Facehugger is the icon of parasitic horror. It forces a reproductive act upon the host, implanting an embryo that grows inside the chest. The horror here is the inevitable betrayal of the body—the creature grows using your nutrients until it kills you to be born.
"You're next," it seemed to say.
We often speak of "energy vampires" or parasitic relationships. To feel "parasited" in a social context means having someone in your life who drains your emotional resources, gives nothing back, and slowly erodes your sense of self. They inhabit your life, taking up space and sustenance, leaving you a husk of your former self.