X. mesmer is an endoparasite, but also a remarkable kind of reproductive predator. It seems to exhibit a degree of executive control or ‘mind control’ over its host organism.
As X. mesmer becomes established in the body of its host organism, that creature grows weak and lethargic, making it an attractive target for opportunistic predators. Mesmer exaggerates this vulnerability by somehow directing its host to seek out dangers it would normally flee. Once another organism approaches X. mesmer‘s host, the parasite’s powerful tubular appendages erupt from the body of its host and suddenly engage the would-be attacker. These writhing appendages seek entry into the body of the predator, where they deposit egg-like globules which will mature into new parasites.
It can be argued that X. mesmer‘s host does not suffer without benefit. The parasite rarely exhausts its carrier to the point of death. Unable to digest foreign tissue on its own, it will even go so far as killing other organisms solely for the purpose of feeding its host. Often host organisms are able to reproduce, producing apparently normal offspring. Moreover, by the careful chemical and psychic ministrations of X. mesmer, many host organisms experience an extension of their lifespan far beyond what would normally be expected. Still, the manipulative X. mesmer reduces its victim to little more than a listless puppet whose behavior appears wholly under the control of its parasite.