Shuki 'Kusatsu' Vengeance has gone through extensive retcons in her time. Her backstory as it stands now I'm happiest with. Child of a human mage mother and a Noble Fae (a species of my own creation, they are a lot bigger than the majority of other faerie tribes, and mostly wingless) father, she is considerably powerful in her own right.

The Noble Fae were almost entirely wiped out in a war with the Dawn Fae several years ago, and a chance meeting with their prince, Vissiel Thorneblade, established a bond between him and Shuki that I'll go into more detail on later.

Vissiel brought Shuki to his family, and that resulted in the death of one of his brothers and his father, upon which Vissiel gleefully seized the throne. Shuki similarly usurped the old queen after fulfilling a prophecy, and then went about establishing allies for this new fae order.