Reaper, by Rachel Vincent, a paranormal romance novella in her Soul Screamers series.
Book Description
Tod Hudson was a typical teenager. He liked girls, sports, food and tolerated his younger brother, Nash. In fact, he had his whole life in front of him--and due to his bean sidhe heritage, it was going to be a very long life indeed. And then the car accident occurred.
Suddenly Tod's future wasn't so sure, and he had to make a choice. Life... Death... or something Between....