"...and they, shades, do come in great variety. Griefeaters, for example, are extremely bloodthirsty but sate their thirst indirectly. Through means of possession. They can possess more than one host body, turning whole villages against each other in a massive bloodshed (See The rivers run red in Wrewick by Gauwill Dery).​

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A hunter is to be extremely prepared not only with potions and shadebane oil to face a griefeater but also with a strong conscience to understand that killing the host is inevitable. "​

-Chapter XXI - Shades, Codex of the Hunt vol. I, various authors​

Griefeaters are incredibly rare shades who are driven by bloodthirst. They reside in lairs, usually uninhabited caves, and when night comes they roam seeking sentients stricken by grief to possess. Upon possession, griefeaters turn the hosts into rabid killers completely out of their minds. The griefeater, as any shade, has no comprehension of sentient physical limits and hosts often die from fatigue, hunger or thirst.​

While they are incorporeal, their limbs can still harm humanoids but a griefeater will hardly ever seek direct confrontation in its natural state.​

There are a few methods to kill griefeaters when they have possessed a host. The killing of a host will result in the shade's release of the host and it will immediately seek another in the vicinity burdened by grief or flee. Often, monster hunters use some form of magic to drive the griefeater out of the host and turn it corporeal where physical attacks can harm it. Otherwise, in its incorporeal state, only silver and magic can damage it. Negating the emotion of grief in the host can also loosen the griefeater's grasp over it.​

Thane Jackdaw, Ashara Raja and Ceridwen Laidyn engaged and killed a griefeater in the forests of Beybrook who had possessed a dozen of hosts. The trio nearly died in the process.[1]​