The rat shapechangers of southern Caheb area are also collectively known as Ratmen. In actuality the creatures are not shapechangers at all. Once they have undergone the change to rat-like humanoid creatures, they stay that way until they die. Usually. There does exist reported cases throughout southern Caheb of ratmen that have somehow been cured of their ratlike state and been returned to their former shape and state. However, they are not many and the whole experience seem to be so hard on the body that they usually do not live happily ever after but instead die of some mysterious illness.
The ratmen that have been exiled from their former communities usually form packs. Some of these packs turn into nasty bunches of thieving bandits and general nuisances. These packs do not fear anything and have turned into effective and mean fighting units. Individual ratmen may not be much of an opposition to an armored knight, but a pack of dozen will rip the said knight apart and eat him alive. A pack of about two dozen ratmen have been known to develop very complex and effective combat tactics and the ratmen communicate in combat by short and high-pitched sounds not unlike the sounds made by actual rats. They are apparently capable of conveying complex messages in a very short time by using this language. Most can still speak the languages they used to know formerly, but the changes in their physiology make this speech strainous, slow and somewhat strangely intonated.
Ratmen are not lycanthropes. Their bite, scratches from their nails or saliva or whatnot does not spread a curse of shapechanging. Strangers to the land often believe them to be cursed by lycanthropy, but the locals know better. But they do spread other kinds of diseases: their teeth and nails are often a cesspool of nasty bacteria that will cause all sorts of infections to whoever they happen to wound. This is usually just a byproduct of their general uncleanliness and dietary which resemble that of actual rats. Rotting carcasses and moldy fruits are fine dining to ratmen.