Dark Sidhe Handbook

What is a Dark Sidhe?

(I made this up)
(This may or may not become canon. It depends on what you all think)
  A dark sidhe is a creature(or some say demon) that lives within one's head. They are the opposite of the original person. Everyone has one,(except for some exceptions) they're just dormant and unconscious. Dark sidhes can begin to gain bits of consciousness for periods of time if the person isn't acting like themselves. It is possible for a dark sidhe to be fully awoken by strong emotions or trauma. There is also a "mutation" where the dark sidhe is just naturally awake within someone. They'll begin as normal, but will gain consciousness at a certain age. Leat and her sister, Takira, both have this "mutation". (Tael and Arikat are their dark sidhes.) For more information, read the other chapters.
  Also, their name is the name of the original spelled backwards, if you haven't noticed yet. :P