I understand what you mean by a hook. Every D&D group needs one to bring the group together. However I don't think this is his issue. In DOS II we're playing the "godwoken" not just some average Joe who happens to get involved. However, this was crucial to the story. I believe that the "tadpole" is a similar scenario. So long as it is relevant to the story and not just an excuse to let a vampire move during the day I don't see a problem with it.
