The Hollow That Lived

Also commonly know as "mothboy" or "mothgirl" the tale of a Hollow That Lived appears in many settlements near the heavy mist regions, because those coasts face the worst kind of Giant Moth infestations and there is rarely a family that wouldn't lose a person or more to them. It is a common urban legend in those parts.
It starts witha tragedy - a child getting lost in the mists, usually following an escaped pet or a domestic animal. One day goes by, two and on the third one, the missing person appears with mothlike anthenas on their head at the highest peak in the settlement, staring off into a distance. Some presume they are staring at the main nest of the Giant Moths and towards the Mother of all Mothers. They do not speak, they do not move until the next sunrise goes by. They seem to be absolutely comatose, but they are able to react to simple commands like walk, stop, turn and so on and are able to perform very simple and limited movements. Some of these tales end with people slowly recovering some of their capabilities, although they are never fully "themselves" again. Other times these tales end with them wondering into the mist for the second time, never to be seen again, or, if you are in an environment where a more scary version would be preferable, they usually lead their family back into the mist with them or hurt them in other way in a sudden violent outburst.
Many medicine people do not like these folk tales as it seem to give false hope to people whose family was affected by the Hollowcurse and lead to preventable harm to either sick or healthy individuals - if it is the hollowcurse, violent end is inevitable and only a diagnosis by a professional can warn people in time. If it is some kind of other sickness, like a response to a sever trauma, these people need also adequate medical response and not be held locked in a room or basement, like in many of these tales, in fear of them "turning" to a monster or wandering back to the mist.