When they arrived at 12 Grimmauld, Remus walked off to find Sirius; while Narcissa invited Harry to sit and have a glass of Butterbeer. Harry was curious, because he had never really had any contact with Narcissa, but he was thirsty and Butterbeer always went down well. He took a drink and watched as Narcissa moved gracefully around the room toward her own seat. The curiosity turned to concern and alertness when he noticed her silently casting spells on the sitting room door. He was reaching for his wand, when she sat down and smiled; "Relax Harry, I'm not going to harm you; I just wanted to have a private chat with you. I told Sirius that you could use someone to teach you how to get along in "Polite" Society; and, honestly, it's not something that you would get at home. I'm sure that Molly and Arthur are very nice people and good parents, but they don't have the background to teach you the nuances of social interaction. The other Weasleys won't need the education, but, you, as the famous "Boy Who Lived", will be expected to maneuver your way through many situations, not just ones where you can claim molestation and have an angry mob do your work for you."