Cimmerian shade

Harry Potter left in London by his aunt meets a stranger who gives him a package and wishes him belated happy birthday. This package will keep him sane at Privet Drive 4 till his eleventh birthday, making him aware of magical world. At least to some degree. AU/darkish/ for open-minded people/ NO bashing/noncan./new subjects at Hogwarts/no pairings (for foreseeable future)/