"Elinor, I have been cruelly used, but not by Willoughby."

"Dearest Marianne, who but himself? By whom can he have been instigated?"

"By all the world, rather than by his own heart. I could rather believe every creature of my acquaintance leagued together to ruin me in his opinion, than believe his nature capable of such cruelty. This woman of whom he writes -- whoever she be -- or any one, in short, but your own dear self, mama, and Edward, may have been so barbarous to bely me. Beyond you three, is there a creature in the world whom I would not rather suspect of evil than Willoughby, whose heart I know so well?" (Chapter 29)

In Chapter 29 Marianne accuses Miss Grey and the rest of the world of being in cahoots against her rather than believe badly of Willoughby but Marianne has little information on Miss Grey at best and part of it is second and third hand—so is this only wishful thinking on her part? The first we see of Miss Grey is that Willoughby is in earnest conversation with her and that she is “fashionable looking” and young in Chapter 28. During the looks that pass between Elinor & Willoughby and Marianne & Willoughby and the shaking of hands and multiple embarrassed looks Miss Grey is neither said to be looking at Marianne & Elinor or speaking of them or to them (as in S&S2). The only incident on which to evaluate her character in this situation is this:

...as if, on catching the eye of the young lady with whom he had been previously talking, he felt the necessity of instant exertion, he recovered himself again, and after saying, "Yes, I had the pleasure of receiving the information of your arrival in town, which you were so good as to send me," turned hastily away with a slight bow and joined his friend. (Chapter 28)

This seems to indicate that Willoughby knows when to high-tail it back to Miss Grey’s side—what could be in that look that would bring Willoughby to heel—perhaps it is the reflection of fifty thousand pounds. However I am not sure Marianne had eyes to see Miss Grey’s drawing Willoughby to herself by hers; Marianne seemed to be focused on Willoughby. The other source of information is Mrs. J who gets her information from a friend who got her information from another friend. The information is a little contradicting too; Mrs. J never heard any harm of Miss Grey but contrarily her guardians will not be sorry to see her enter the marriage state and leave the ward state. There is a little evidence that the future Mrs. Willoughby may be controlling (bringing Willoughby to heel) and a bit combative by frequently disagreeing with her female guardian. I think Miss Grey might be a candidate for disparaging Marianne but I am not positive she is guilty of it yet.

"I never heard any harm of her; indeed I hardly ever heard her mentioned; except that Mrs. Taylor did say this morning, that one day Miss Walker hinted to her, that she believed Mr. and Mrs. Ellison would not be sorry to have Miss Grey married, for she and Mrs. Ellison could never agree." (Chapter 30)

:D