This trope focuses on subtle infiltration and takeover. A parasite enters its host through vulnerable points—mouth, genitals, wounds, or during sex. At first, the host feels only mild symptoms: warmth, arousal, strange cravings, or missing time. Over time, the parasite asserts control—sometimes blending its will with the host, sometimes erasing it. The parasite thrives on secrecy, often feigning normalcy while using the host’s body to spread or breed. Erotic tone: the host’s sensations are heightened, turning corruption into seduction. Themes: corruption from within, secrecy, erotic horror, intimacy as a vector for invasion.