Part of my life, how?

I'm no ordinary human. In fact I'm not even human. I'm the impossible one and no one can tell me what to do. I know I look human but I know what I am.

All the demons want me stone dead except one

No one knows why and what the leader wants with me

But all I know is that he wants me to be his girl but I like someone else

Maybe its something to do with my heart or my blue gem that cracked inside my left leg and spreaded all over my body.

No one knows. I don't know either. I will find out and won't give up until I fade away!