[EDIT: now crossposted on the tumblr]
This is something I worked out a while ago...like, in the last two years? 2014ish maybe. Because I was reading yet another werefic based on hilariously inaccurate theories of grey wolf social structure*, and I decided to finally hammer out my headcanon for D.Gray-characters being wereshifters. (Also the biologically-enforced-gender-role dynamics, but I'm leaving out that part because it's kinky but ultimately pisses me off.)
Assuming some humans manifest some sort of magical spiritual totemic bond with animals of a specific extant species of carnivore, but instead of being able to wolfwhisper you instead turn into a wolf; limiting the species pool to commonly known (/culturally significant) charismatic animals in a few of the Carnivora families, because most people don't know or care about fossa or binturong**.
(I apologize in advance for the taxonomy geekery contained below.)( unnecessarily recursive footnotes )