I adopted Yuna from jakereallyishappy (DA)
and Dissonance from xXNight-StalkerXx (DA)

their "theme songs" are:
Yuna - After midnight
Silent Hill: Shattered memories - Acceptance
Sixx A.M. - goodbye my friends
and lastly
Evelyn evelyn - evelyn evelyn

I'm still working on the story but basically Yuna is haunted/possessed by a powerful demon and ends up killing everyone she loves and cares for. the demon demands blood, and yuna is powerless to keep her from TAKING it.

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Edit:

she was the first black cat born into her family in many generations (in her family all the black cats born and females, whom bare a curse. the curse is the demon partially possessing their body. they bare this demon so that it cannot go out freely into the world and commit evil. and when they die they must be put into a river so that the demon still cannot escape. (at least until the body reaches shore again or their bones are worn away, afterward a new black cat will be born))
so her family keeps her away from modern society (of which she is fascinated by) until one day she runs away and starts a life all her own. lives on her own, gets a job, and even starts attending public school. she makes friends too!
the only problem is that she's starting to hear, she, and lose control to the demon on occasion. and the demon wants to kill her friends.