Thank you for your post. This and the one above really bring out the contrast in the two pairs of sisters.

Your post made me think that Lucy is almost an opposite of Marianne as Marianne was at the start of the novel. Lucy is all 'sense' and no sensibility, no feeling. Given the hand of a penniless girl of good birth, she plays it as rationally and shrewdly as she can. She takes Elinor's social manipulations (eg back when Elinor was getting some time alone from Lady Middleton to talk to Lucy) to extremes, always displaying the feelings that suit her best. She has Edward right to the end convinced that she cares for him (see chapter 49), so I think we can be confident she does not care for Robert apart from his income.

Where Marianne prided herself on her truthfulness and never saying what she didn't feel, Lucy appears to always say what she does not feel, or lie in other ways. Is there a speech in the whole novel where she speaks the truth in both words and tone? If so I cannot bring it to mind now.