A Demon's Angel - FINAL VERSION

Oakley Vespertine and her family are angels, and they've come to Earth in order to find a demon that has been killing civilians. The Fates don't like it when creatures mess with their plans, so they send out demons or angels from the Guard to handle them as quickly as possible.
While Oakley and her brother Parker are at the high school; pretending to be teenage siblings and hoping they find their lost older sister, they meet a friendly demon named Ryker Dagon.
Ryker and Parker become best friends in what feels like minutes, maybe it's because Ryker has a certain charm to him. A charm that seems to be pulling Oakley in the same way.
A little while later, they run into a less than civilized demon named Axel Solace. Oakley quickly grows irritated with the perverted behavior exhibited from this demon.
Ryker and Oakley quickly grow close, and she confesses a huge secret from her past, which invokes a curse placed on her. The one who cursed her is none other than her first love, Zadrial. All the while Axel remains a constant thorn in Oakley's side, but over the course of some life-threatening situations... she seems to be growing fond of him.
With some growing romances, a spark of hope that they'll find their sister, and Zadrial hot on her tail... will this mission be completed?