The Fey

The Fey are the a broad group of interrelated magical species, ranging from unconscious minor sprites and magical animals up to the powerful Fey Lords and their courts of humanoid courtiers. They inhabit a Near Dimension called Faery, one of the closest of the planes to Soma.
Fey are incredibly diverse but share a few key characteristics. The first and most telling is their utter incompatibility with cold iron, a special metallic substance that burns the Fey like fire, pierces their natural resistances and confounds their inherent abilities. From the smallest to the great Fey, this cold iron aversion is nearly absolute. 
Fey also tend to possess powers of charm, illusion and allure. The Fey are inherently otherworldly and supernaturally attractive to most mortals. The intelligent Fey often delight in games of persuasion and bargaining, sometimes with cruel results. For all of thei rinherent tendencies towards misdirection and confusion, Fey never lie or break their word. Because of the manner in which their power emanates from their fundamental identities, Fey are incapable of misrepresenting themselves in this manner. A fey is physically incapable of knowingly breaking a sealed bargain and even an accidental or minor failure to fulfill results in a severe reduction of power and even a state of ongoing pain.
For similar reasons, the Fey are particularly susceptible to the magic of True Names. Fey never change their fundamental nature and so their True Names are static.