Angels' Blood (#1) by Nalini Singh
Elena's world is set in basically an alternate universe. Archangels and angels rule the world. They create vampires because of a super secret reason. Humans still have their governments and people to rule the humans but it is basically a farce. Humans really are nothing compared to the angels and the vampires.
Elena is the bad ass heroine who reminds me of Kate Daniels by Ilona Andrews. Elena is a Guild Hunter and also hunter-born. When vampires are made, they choose to fall under 100 years of service to their angel. When the vampires decide renege on this contract, the angels hire the Guild who is dispatched to find said vampire. There is a lot of violence in the field and can be extremely dangerous. Because Elena is hunter-born, she can track vampires by scent and she is much stronger and faster than the average human.
However, only certain people can become vampires. Elena is hunter-born. She can track vampires by scent. Her natural abilities makes her stronger and faster and highly talented for her career choice. It's because of her ability that Raphael, the Archangel of New York, wants her to track down an archangel, a job that will certainly get her killed.
Elena has a horrible past that likes to pop up and torture her. Her father disowned her because she is hunter-born. She and her father haven't talked for 10 years and her sister doesn't really talk to her much either. Elena's friends become her family instead. I like the relationship between Elena and Sarah. Ransom cracks me up. Singh did a great job with the supporting characters.
Basically....read this freaking book.
After reading all the titles from the rest of the series, this book should have been titled Archangel's Blood. It would have been so much better.