On this re-reading, what struck me the most was that Mr Elton's insulted feelings of outrage on being presumed to be the lover of Harriet are *precisely* the feelings that Emma harbored about Robert Martin on behalf of Harriet. In the following dialog of Mr Elton from ch15, I have substituted Harriet (in brackets)for Elton and Robert Martin for Harriet:-

"(Harriet) think seriously of (Mister Martin)! (Robert Martin) is a very good sort of (man); and I should be happy to see (him) respectably settled. I wish (him) extremely well: and, no doubt, there are (wo)men who might not object to -- Every body has their level: but as for (Harriet), (she is) not, I think, quite so much at a loss. (She) need not so totally despair of an equal alliance, as to be addressing (her)self to (Mister Martin)!"

It is indeed ironic that based on his proposal,Emma should think him presumptous. Her opinion of Mr Elton, could very well be said to be Robert Martin's opinion of Harriet, after Emma has mis-guidedly puffed her up with self-importance. This narration is from ch16, and again I am substituting the characters...

"It was dreadfully mortifying; but (Harriet) was proving (her)self, in many respects, the very reverse of what (Mr Martin) had meant and believed (her); proud, assuming, conceited; very full of (her) own claims, and little concerned about the feelings of others."