Unfortunately this is another sequel but I highly recommend this series. The back of this particular book has a quote about this being an heir to the Twilight throne. This series is so much better than Twilight could ever be. The books follow Rosemarie Hathaway as she attends a secret school for Moroi (vampires) and dhampir (guardians). Rose is a dhampir and her best friend Lissa is a Moroi, but not just any Moroi - the last of a royal blood line. This book has some teenage romance but follows the girls as they struggle to survive in a changing world that is filled with dangerous vampires they call Strogoi.
This particular book is the 5th of the series and it is heartbreaking. Not to spoil too much but Rose is stuck trying to make her relationship with a Moroi work while trying to save Dimitri, her former and greatest love. It has a little teen drama but this is so much more serious than Bella and Edward's little on again, off again relationship. More importantly Rose is a strong character and is not afraid to take a few lives as she fights to find her place in this world.
The first book is Vampire Academy and I really strongly suggest giving it a try.