This sounds very interesting. I will have to see what else I can cook up for ideas, but my initial thought is a sort of blend between Poison Ivy and Audrey II. Think a green human body with vines growing out, twisting around their arms and legs, vine/leafy 'hair' and a venus fly trap/Audrey II-style head. 

A second idea is an older gentleman that is a horror/mystery novelist. Depending how widely-known the supernatural are meant to be, perhaps is oblivious to the existence of them or has somehow missed the memo. Anyone with non-human features is regarded as a 'talented cosplayer'.