People who can change form from human to animal. The animal usually has something to do with their heritage and predisposition.
The Jekyl and Hyde Affect[]
Though the transformation itself is triggered by strong emotions, the disposition of the beast is determined by the disposition of the human. If a shapeshifter is docile, controlled, or overly proper as a human, the beast will be viscous. If a shapeshifter is ravenous or lude as a human, it is docile and sweet in beast form.
Most tribal cultures where shifting is common, they have discovered a means of balance that mainly consists of giving in to impulses without giving in to one's primal nature.