Found: Sci-fi/Fantasy from the early 2000

When I was in high school I read a book about a teenager from the future who was sent to the past for protection from his evil cousin. The people he thought were his parents were just his bodyguards and warned him not to stand out. Of course he does this and has to go on the run. The only other details I remember are that he has a dog sidekick who is psychic and a girl who can shapeshift and fly I believe that helps train the main character in his abilities. His evil cousin was named Dargon, or Dagon or something close to dragon but that's all I recall outside of the cover being blue. I do remember that it was about 08-09 when I read it, and the title has slipped my mind

Firestorm by David Klass.

Thank you! That title has slipped my mind for so long