I am puzzling over Mr Palmer, and what purpose JA had for including his character in S&S.

I can't fit him into a category of sense or sensibility, as per the novel. He also doesn't seem to fit into the contrast between polite people, or people who claim outward politeness (Lady Middleton), and people who are not nasty but are often rude (Marianne, Sir John, Mrs Jennings). He doesn't appear to serve a plot purpose like Mrs John Dashwood. Is he meant to illustrate someone who is both rude in behaviour and cruel in motivations?

This passage here makes me wonder if he is meant to be compared to Marianne, in showing a desire for superiority by distinct rudeness (as opposed to her overweighting of feeling).

Elinor was not inclined, after a little observation, to give him credit for being so genuinely and unaffectedly ill-natured or ill-bred as he wished to appear. His temper might perhaps be a little soured by finding, like many others of his sex, that through some unaccountable bias in favour of beauty, he was the husband of a very silly woman -- but she knew that this kind of blunder was too common for any sensible man to be lastingly hurt by it. It was rather a wish of distinction she believed, which produced his contemptuous treatment of everybody, and his general abuse of everything before him. It was the desire of appearing superior to other people. The motive was too common to be wondered at; but the means, however they might succeed by establishing his superiority in ill-breeding, were not likely to attach any one to him except his wife. (chpt 20).