Wererats (as most lycanthropes) are rather unpleasant creatures. In my Dustchaple Downs fantasy RPG setting, there are quasi-wererats that are not true lycanthropes, but are posessed of many lycanthropic attributes. For starters, the quasi-wererat cannot transform into a rat or even a half-rat/hal-man. Instead, they are humans that are posessed of a sort of spirit/animus that gives then some interesting features. In the case of a quasi-wererat, they have elongated incisors, sharpened senses (particularly hearing, smell, and vision). They usually have elongated whiskers that they can employ to help feel changes in the air around them, giving them another sensory perception that normal humans do not. Plus they are usually tough bastards as well, being able to resist diseases and other unpleasantness that would be very harmful to a normal human. Enjoy and happy gaming!
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From @xyanthon