Personal Demons by Lisa Desrochers

From GoodReads: Frannie Cavanaugh is a good Catholic girl with a bit of a wicked streak. She's spent years keeping everyone at a distance—even her closest friends—and it seems her senior year will be more of the same...until Luc Cain enrolls in her class. No one knows where he came from, but Frannie can't seem to stay away from him. What she doesn't know is that Luc works in Acquisitions—for Hell—and she possesses a unique skill set that has the King of Hell tingling with anticipation. All Luc has to do is get her to sin, and he’s as tempting as they come. Frannie doesn’t stand a chance.

Unfortunately for Luc, Heaven has other plans, and the angel, Gabe, is going to do whatever it takes to make sure that Luc doesn’t get what he came for. And it isn't long before they find themselves fighting for more than just her soul.
But if Luc fails, there will be Hell to pay…for all of them.

I didn't know what to expect when I started this book, I had heard good reviews, but I was still disappointed by the let-down from Halo.  But even after just a few pages, I knew this book was not going to let me down. 
The characters were really enjoyable and really brought the story to life.  I enjoyed the twists and turns, and especially liked the ending.  I hope to see this become a small series, I really want to know what comes next.