Hmm. Doesn't seem very HP for some reason; just a generic story with Harry's name plugged in. Maybe if you started with some accidental magic instead of the Dudley chase to establish the story and then introduced the werewolf as a twist. Also having the wolves and vamps targeting Harry specifically seems wrong what with the blood wards supposedly hiding his location. Maybe he should accidentally encounter the werewolf being pursued by the vamps...
Author's response
The blood wards will be explained later. don't be impatient now. lol