Faeries are generally considered to be pretty benign creatures, even bordering on the helpful. Since I’ve been looking at the faerie lore of different countries. I’ve highlighted faeries that were less pleasant. Several of them, such as the beansidhe, aren’t actively involved in the harm of humans. This isn’t true of a lot of the faerie. A great many of them directly impacted the lives of humans- and not in pleasant ways.
The Alp-Luachra (the joint eater) is an Irish faery with some…bizarre feeding patterns. Often taking the form of a small lizard the joint eater would slip down the throats of a person sleeping next to a stream or river. While in the stomach of the sleeper, the faerie would feed off of the ‘essence’ of the food more than the food itself. It is said that eating lots of salted food could prevent this from happening.
The problem with the joint eater is that the longer that the person is haunted or ridden by the faerie, the thinner they would become. The joint eater would take half of whatever is consumed, leaving the person to slowly starve.