She's rather used to being the focal point of her group of friends, if not in an obvious way, and it's probably safe to say her attitude is borne of habit. Narcissa is well-bred and her society's equivalent of high born, and it shows in almost every nuance of her behaviour.

"Oh? A great harp, or a lap harp?" Over her shoulder as she leads the way out of the kitchen and towards the grand staircase. The room she'd found the piano in was well insulated with lovely acoustics, and she found it easier to simply leave it there... "it" being a grand piano in the traditional sense. "Here she is... and she's imported; her maker's mark is Pleyel."

Which might have convinced her to take this particular abandoned manse over any other; her own piano is a Pleyel.