To take some of the monster design theory being tossed around and pin it down, here is what I'd like the jackalwere writeup to look like:
Description jackalwere behavior & psychology, terrain, organizational structure & culture, treasure carried/stored, ecological niche, track & sign, common tactics, and possible allied/companion hunters.
Then three hooks a DM can choose from about how they fit in the overall lore of D&D:
- In the default Forgotten Realms setting, jackalwere are created by the demon lord Graz'zt thru dark magic corrupting the animal spirits of jackals. They serve as underlings to the Lamias, greater creations of Graz'zt, along with his six-fingered cultists.
- In other settings, such as Greyhawk, Mystara, or Dark Sun, jackalweres fit in more with pseudo-Egyptian cultures, and may be favored priests who worship the dark god Set.
- In other settings, like Ravenloft or Planescape, jackalweres may be the result of a terrible curse on anyone who steals from a dying man and lets him perish. Their mimicked human calls are an attempt to plead the gods for mercy from their curse, unwittingly attracting more victims who they cannot help but slake their bloodlust on.
Let FR be their vehicle for all the default stuff as it seems to be going, letting FR bear the burden of any default effect. Use definitive language with FR monster lore, e.g. "jackalweres are created by the demon lord Graz'zt." With example monster lore for other settings, however, use conditional language, e.g. "may be." Let it be up to the non-FR DM to decide which, if any, of the proffered monster lore fits into their campaign.