A little known but amazing book by Neal Shusterman, a highly recommended author. Neal Shusterman also wrote the Skinjacker Trilogy (Everlost, Everfound, and Everwild) Unwind, along with several other science fiction/fantasy novels. All are very well written with amazing plots and lovable characters.
Bruiser and Unwind are two of my all-time favorite books. If you haven't read them....You need to.