The Mesmeri are the recombined elementals of Emotion, born from Light and Dark. Dangerous creatures with no physical form of their own, they live by possessing a human host and feeding off of their emotions, thoughts, and creativity.
Although some Mesmeri destroy the free will of their host body, others allow the original being to have their own separate identity, with the only condition being that the Mesmeri can still siphon their essence to sustain itself. A Mesmeri can actually be a source of inspiration to some, as it increases the emotional and inspirational capacities of the mind.
However, all hosts possessed by Mesmeri die within seven years, and must frequently be replaced. Once the host is gone, the mesmeri exists as a shifting coil of white smoke that can invest and possess anyone that breathes it in. It has been suggested that the dreaded Whisps are in fact Mesmeri corrupted by the Abyss.