Kergillians are crustacean-like creatures from a distant star. They implant their own brains into those of humans and other life forms. While voluntary hosts are promised hightened senses and expanded consciousness, the implant soon takes over the host's brain. A host for a Kergillian often has strange urges and cravings. The Kergillians' understanding of the human neuro-system has allowed them to invent several types of stun-weapons.