This is an interesting question because it does not focus on the far more visible character of the niece...instead, it focuses on the less visible character of the aunt. To give you an answer, though, If I had to make a decision about how Mrs. Sappleton could BEST be described I would use the phrase "matriarch of the family."
Why do I think that? Well, it was something in the way that the woman carried herself. A matriarch is a female head of the family (or tribe.) Here are some of my reasons:
- I suppose my opinion of her as such started when she came down the stairs "fashionably" late to receive her guest. To me there is something stately about that.
- Then there is the way that she leads the conversation "She rattled on cheerfully about the shooting and the scarcity of birds, and the prospects for duck in the winter" and his inability to steer the discussion in a different direction. To me, this suggests a woman of strong personality.
- She makes a comment about the men that I feel shows that she believes herself a little bit better than them: "they'll make a fine mess over my poor carpets. So like you menfolk, isn't it?"
- She is bored by Mr. Nuttel talking about himself and has to stifle a yawn. This, to me, shows a certain disdain for men (though perhaps just this particular one) and a presumption of superiority that can't be marred by the faux pa of yawning.
- She is very interested in the return of the men. She appears to like to know where people are, what they are doing, and when they are coming back. That, to me, implies power.
- Her husband, two young brothers, and her niece are all either living at the house or are visitors there. This shows that the orbit of the family, to some degree, revolves around the mom.
That's my two cents worth: matriarch.