Austen routinely uses both direct characterization and indirect characterization to draw the picture of her characters. She began using this dual approach to characterization in Pride and Prejudice and Sense and Sensibility and continued with it right through to Persuasion and Lady Susan.
Direct characterization: In direct characterization the narrator (in this case Austen' authorial third-person narratorial voice) makes direct remarks about and explanations of a character's personality traits, feelings, thoughts, psychological motivations and reactions to events and to other characters.
Austen initiates characterization of all the principle characters in this direct way in Chapter 1. [It is interesting to note that Austen introduces secondary characters in Sense and Sensibility before introducing primary characters.] Using Marianne as an example, the narrator explains that while Marianne has admirable qualities of mind and heart ("sensible, clever, ... generous, amiable, interesting"), her dominant trait is excessiveness, with "no moderation" and lacking the ability (or inclination) to be "prudent":
She was sensible and clever; but eager in everything: her sorrows, her joys, could have no moderation. She was generous, amiable, interesting: she was everything but prudent. [Narrator's direct characterization]
Indirect characterization: Indirect characterization is when conversation between characters about themselves or about other characters indirectly reveals a character's personality traits, feelings, thoughts, psychological motivations and reactions to events and to other characters. These qualities are implied by what is said. For example, what do I imply about Marta if I say to you: "Marta turned red in the face and clenched her fists when she heard what Angelina did." (I imply that Marta has a very angry temperament.) In Chapter 4, Marianne indirectly reveals two more points about her characterization through her conversation with Elinore regarding Elinore's feelings for Edward Ferrars.
First: Marianne's own remarks indirectly confirm and enlarge upon the narrator's direct comments about her traits; Marriane's statements prove and show the extent of her disinclination for being moderate and prudent.
... [Elinore] tried to explain the real state of the case to her sister.
"I do not attempt to deny," said she, "that I think very highly of him—that I greatly esteem, that I like him."
Marianne here burst forth with indignation—
"Esteem him! Like him! Cold-hearted Elinor! Oh! worse than cold-hearted! Ashamed of being otherwise. Use those words again, and I will leave the room this moment."
Second: Marianne's own remarks indirectly reveal her "sensible and clever" qualities when she silently deliberates about how to mitigate her reply to Elinore 's question ellicting her opinion of Edward so that (1) she does not offend Elinore yet (2) tells the truth since, as per the narrator's direct comment, Marianne found it beyond possibility to say what she did not truly feel (a trait that can be good or bad as is demonstrated after the ball in London).
"I hope, Marianne," continued Elinor, "you do not consider him as deficient in general taste. ... I am sure you could never [think that and] be civil to him."
Marianne hardly knew what to say. She would not wound the feelings of her sister on any account, and yet to say what she did not believe was impossible. At length she replied:
"Do not be offended, Elinor, if my praise of him is not in every thing equal to your sense of his merits. ... I have the highest opinion in the world of his goodness and sense. I think him every thing that is worthy and amiable."