The Demon's Princess

Humans have it all wrong.
Demons aren't the horrific creatures of legend. Instead, they look just like us, only they tend to be just a little bit more --taller, stronger, faster, smarter--only those who have turned to the darker forms of their abilities over their element can warp their minds and their bodies to the furthest extents of the horrors of legend, but the creatures that once were demons have been hunted to near extinction. Or so the rest of the residents of the afterworld were led to believe.
Angels? They're not perfect beings. Vampires don't exist, angels are the only beings other than the demons who are equipped with fangs, the difference is, many of the angels use them. They don't need blood to survive, instead, it's more like a drug to them, one that is easy to become addicted to and extremely difficult to ever lose dependence upon. Those who have done this are sometimes referred to as "fallen".
Witches are the only being humans got anywhere close to right. They are both good and evil, determined by the nature of spells they cast, but they are not old crones covered in warts cackling evilly over a bubbling cauldron. Most fit in easily, but a few are just a little too different to pass the muster.
Aria is a mixed-blood. The element under her demonic control is fire, the most volatile and fierce of the elements. A raging inferno lives in her blood, shifting under her skin in a manner revealing the enormity of the power she contains whenever her emotions rise. Control isn't always easy for her, being cursed during your life in the human world by your own father will do that to you. She lived in a time where if accused, witches were burned alive at the stake. Her demonic affiliation with that particular element should have saved her, but a spell stripping her of all supernatural traits cast upon her and her brothers allowed her father's curse to be enacted.
For Aria, death wasn't the end of her life, if anything, it was a new beginning.