Austen begins to trace in Henry. The everyday truth she relies on is some people bring out the best in others and some the worst. This was to be fundamental to Emma . As many of us do Emma's behavior is a function of the people she's with. Fanny brings out the best in Henry.
Character is habit.
If we are able to act in a certain way, understand its value, and keep to it, after a while we become that. He never speaks of it. He is tactful and doesn't go around boasting about his good deeds. In fact I would say that Henry proposes to do for Fanny what no-one has thus far. To make her the equal of those around her.