The Thrall concept is yet another variation of the “vampire” theme. Instead of being infected by a “virus” the Thrall is a parasite which takes over the body and mind of its host for a few years. Eventually the body wears down and a new host is selected to receive the next queens eggs. Additionally the Thrall lives in a hive culture with a single reproductive queen leader and her drones the “hosts”. Humans all considered the “Prey” that feeds the hive the blood they need. Humans can also be Herd if they voluntarily feed the Hosts.