The Yalthea is a beast borne from the early eddies and flows of chaos. As the structures of the past break down, large amounts of psychic energy are released as what was once permanent, worth basing one's life around, is destroyed. It is from this chaos that the Yalthea emerges, and it is from this is that it receives its subsistence. Although coming in, by definition, a variety of shapes and sizes, the Yalthea are generally grouped into two broad categories: Greater and Lesser.
The Lesser Yaltheas are those born from small-scale events: a family falling apart, a fire in a crowded theater, or a power outage in a large city. Although the majority of Yaltheas are of this type, they are not to be considered especially dangerous. Their relative size is small, and their appetites match their appearance; most are content with small-scale pranks and mischief. These Lesser Yaltheas may be considered akin to some of the less malign varieties of fey.
The Greater Yaltheas, however, are born from events which shake societies to their roots. Although most revolutions and assassinations merely produce many thousands of Yaltheas of the Lesser variety1, those that upend a particularly long-standing form of government are likely to form several Greater Yaltheas at once. It is said that with the fall of the Bourbons, the streets of Paris were overflowing with "horrid men yipping and howling, their long, splotchy tongues dangling [to their] knees." This variety of Yalthea is of a far more rapacious appetite, only finding adequate sustenance in the creation of widespread chaos. The more cunning among the Greater Yalthea often use their mutable forms to their advantage, sowing distrust on top of distrust, until each man is at his brother's throat. One particularly cunning Yalthea, known only as Louis, overcame his kind's natural disinclination towards order and received a commission as a tribunal judge in the People's Revolutionary Court, whereupon he is recounted to have sentenced many thousands to death for crimes uncommitted, while pardoning many thousands more upon a whim. Given the general viciousness of such upheavals that spawn the Greater Yalthea, it may be some time before their activities are brought to account.
Yaltheas have no fixed appearance. Although each has an initial form while it first comes into existence, to ask about a Yalthea's first form is considered exceedingly rude. While, if concentrating, they can hold a form indefinitely, they find this to be a highly unpleasant sensation. Most forms of the beasts incorporate aspects from nature, such as dogs, deer, or grass. However, with the rise of the city as the center of the world of man, many have begun to incorporate bits of the urban environment into the visage, appearing with a window for a mouth, or steel cables for arms. These changes in are involuntary, and the Yalthea are largely unable, and indeed, unwilling, to control them. Despite their variable appearance, all Yalthea in all forms have a mouth, of one kind or another. The opening of this mouth will reveal a long pink tongue with a large blue mark upon it. The meaning of this characteristic is not as yet understood. The Yalthea detest the sound of clocks, and will flee it whenever possible. They also dislike the scent of honeysuckle; this may be used in securing an agreement with a Yalthea2
A brief note: Despite the description, it should not be taken that the Yalthea, Greater or Lesser, are creatures of evil. They are just as likely to save a good man as to condemn him, and their notion of the world holds no room for good and wicked deeds. They are merely upheaval given flesh; to condemn them as wicked for their actions is as absurd as condemning the wolf for its killing of sheep.