In Mansfield Park, narrow views of morality often clash with more open and lax moral codes. All characters deal with questions of how to behave and what is right or wrong, though some stress over it more than others do. For everyone, right and wrong principles are a matter of judgment. While characters like Edmund and Fanny feel that morals are universal rules, and are right for everybody, others take a much more relative view of morals. Making moral decisions and judging situations often leads to judgmental behavior. However, lax morals can lead to hurt. There's a fine line between making judgments about people and situations and just being judgmental.
Fanny is one of the few truly moral people in the book because she sticks by her principles no matter what.
The narrator often treats Edmund and Fanny ironically, or with a lot of humor and criticism. Though they are presented as "moral," the narrator doesn't really agree with the morality of Edmund and Fanny.