 The tutelage is painful not because of a sadistic urge, but to teach Molly in a manner that is both lasting, faster, and more informative than Harry's slower, gentler methods.After seeing the results as a ghost he realizes that he's been "babying" Molly in her training resulting in her being less prepared, less capable and less knowledgeable without him.The historical inspiration for the Leanansidhe is a particular type of faerie who is the inspiration for mortal artists and performers.