Emma thought that knowing so many flattering words has been said in his favor. The young man was very handsome: his height, posture, manners were immaculate, his expression was the same inspiration and vivacity as his father had in his eyes and insight.
“Your amiable young man is a very weak-hearted young man if for the first time he was faced with the need to insist on himself and do the right thing, contrary to the will of others. In his summer, it would be time to get used to being guided in his actions by duty, and not by self-interest.” (Mr. Knightley about Frank Churchill)
In the first volume of Emmy, Frank Churchill is often mentioned and never met. Here is the quotation that illustrates him a lot. “So I'm here, at the beginning of the second part, about the fact that we were called to rate Frank Churchill for myself, and I realized that our two most important sources of judgment (Emma and Mr. Knight) are distorted to understand fully.”
Emma finally realizes her feelings for Frank Churchill. Nevertheless, she calms so much that they are just friends in their eyes. Two chapters in the third volume from Mr. Knightley's view (Chapters V and VI) explain perfectly, even if he is biased, he also has legitimate fears of the actions of Frank Churchill by his two relatives. Jane Fairfax and Emma Woodhouse have reason for him from the "double conversion" of suspicion (Volume III, Chapter V).
Frank Churchill in the Essays