Specific attributes: A frerwyn can change from one form to another at will. While in a form, they have full self-control, though their minds are limited to the nature of the brain of that form. They can also mix the attributes of any two of their available species; thus, they can become a human with the eyes of a cat, or a cat with the nose of a wolf, or any other imaginable combination. They cannot, however, normally mix the attributes of all three species.
The transformational power of the Frerwyn is tied to the phases of the moon. The fuller the moon is, the more quickly the change takes place; on a full moon, it can occur in less than a second, depending on the Frerwyn in question and the degree of change taking place. Right before a new moon, the transformation is as slow as five or six seconds, and in some cases may take up to eight or nine seconds. During a new moon, the transformation cannot be done at all, and Frerwyn are always careful to pick a suitable form in advance since they will be stuck that way until the moonlight returns. The effect of the moon's phase works regardless of physical barriers, and lingers after the moon has set, until roughly the time that it rises again, so even if a full moon is not actually up, if it has been in the sky within 12 hours or so, its effect will remain.
Additionally, while the moon is full, the Frerwyn are able to transform into a creature known as a Greyn, which mixes the attributes of all three species to the greatest effect. The Greyn is extremely strong, agile, quick to respond, intelligent, and has highly acute senses. Because of this, the territories of the Frerwyn fall silent during the time of the full moon, as all living things take refuge lest they stir the ire of the Greyn.
Finally, Frerwyn have a weakness for silver; even when cold, it burns them as though white-hot. Frerwyn are known to say that the moon's rays feel like the warmth of a fire, though slightly different, and that the touch of silver is like a more extreme version of that warmth. Because of this and the similar color, many have conjectured that the energies emitted by silver and the moon are somehow related.
Culture and social structure: Frerwyn consider themselves of each species and none, taking no favoritism over any of the three, though many prefer one form over another in general. Within their territory, they hold what is known as the Pact, an accord that no wolf, human or cougar may kill a member of the other species. If such a thing happens, they are subject to the harsh and often fatal justice of the Frerwyn. The Frerwyn hold themselves to this Pact as well, and never hunt the native wolves, cougars and humans that live nearby, except in cases of socially-accepted retribution. However, those species are still wary of the Frerwyn, partly out of supernatural fear of their shape-shifting powers, partly because of the profound control over the area that their powers give them, and also because consorting with the Frerwyn inevitably lends itself to all manner of complications. For example, the child of a Frerwyn is always a Frerwyn, regardless of whether the bearer is a Frerwyn or simply a natural animal. This can lead to difficulties when a she-cougar suddenly finds a sometimes baby or wolf-cub on her hands, and finding the actual father is often a difficult prospect.
Frerwyn live in a highly scattered social structure, some living in town-like settlements, others moving in nomadic family packs, and still others taking a loner's lifestyle, so there are a number of potential radical elements in Frerwyn society. However, even the loners are generally kept track of, and there exists a certain amount of communication between all Frerwyn communities, regardless of their preferred form.
Some Frerwyn are given to a certain degree of arrogance, pushing around the outer species out of a sense of superiority. Their reasoning is that they have a singular perspective of the world, and that this three-fold view gives them an unparalleled understanding of nature. Recently, a movement in this direction has become increasingly popular.
Language: when in wolf or cougar form, Frerwyn use the natural languages of those species, as the forms are ill-suited to alien forms of communication. When in human form, however, they tend to use a human vocabulary, taken from a neighboring human kingdom and altered to a very distinct dialect over time, but tempered with the grammar and syntax peculiarities of the other animals. Word order is based on wolf language, as well as words describing times and places, and also honorifics. Cougar language lends itself mainly to insults and colorful exclamations.
The resulting sound of Frerwyn language is odd, punctuated by growls and hisses and certain unusual gestures and possessing a certain directness and simplicity that many human languages lack.
Because the moon is of such primary importance to the Frerwyn, they keep not only a lunar calendar but also a lunar clock. A day begins when the moon rises and ends when it rises next, and night is considered that period when the moon is not in the sky. This sense of time is said to come from the wolves. The position of the sun is largely ignored by the Frerwyn; daylight has little meaning to a race who can adjust their night-vision at will.
Because of their extreme adaptability and the sheer power of the Greyn form, the Frerwyn are considered a class A threat.