You, like most other children, could not remember the circumstances of your birth. However, unlike most others, you could not remember the one who gave birth to you either. You were raised by your father in a small cottage a full day's travel from the nearest village, which might seem like a quiet life, except for one detail.
Every night after the sun set, you turned into a demon. During the day, you actually seemed quite normal, a regular human. That is, except for a small abnormality: a tail. But that could be easily hidden in normal circumstances, such as during trips to the village. At night, on the other hand, when the powers of darkness were at their strongest, you changed. It had happened as long as you could remember, and from what your father told you, since you were born. Even as an infant, your father would place you every night in a hidden underground room that was more a cage than a bedroom. You still spend every night hidden away down there, although now you are aware of yourself during your change and somewhat in control, not simply the victim of your demonic instincts.
You do not doubt that your father loves you, his daughter, despite him being a regular human. In fact, you know he loves you, or else he would never have spent so much time and effort keeping you alive and safe. After all, if any other human found out about you, your life wouldn't be worth a red cent. Full-blooded demons probably wouldn't care much for you either, other than as a possible meal. Nevertheless, you both knew this quiet life would only last so long.
And so, now that you are age 20 and your father died a week ago, you have a decision to make. Do you squirrel yourself away in the woods for the rest of your life, praying no one discovers your secret, do you wander the land aimlessly, or do you scour Serra for a way to stop your nightly changes by any means possible, even if it means becoming a full demon?