[ Derek sighs. ] I really don't know, Stiles, I just know that a lot of our makeup is different than humans. It's not like we're offering ourselves up to science for experimentation. If someone out there's figured it out, they haven't told me. [ He frowns briefly, thinking. ] I know that the.. black substance that we expectorate when tainted with wolfsbane or something like it is our body's way of rejecting the poison, kind of like how white blood cells work in humans, only way more violent and gross. It has something to do with the healing process, and how ours differ.