One of Jane Austen's most brilliant stylistic techniques is her skill in developing character through dialogue. As an example of this in Pride and Prejudice, recall Elizabeth's first conversation with Charlotte Lucas about marriage. In this dialogue, Austen develops Chalotte's character by providing the intellectual rationale and the motives for her later acceptance of Mr. Collins' marriage proposal and for the foundation of what Elizabeth considers her inexplicable happiness and contentment in her married life. In the same dialogue, Elizabeth's character is more deeply developed so that her inability to see a perspective that opposes her own is revealed, which is a critical aspect of Lizzie's character as it helps fuel the escalating conflict between Lizzie and Mr. Darcy.
Another instance of how Austen adroitly uses dialogue to develop character is that which initially introduces Elizabeth to Mr. Darcy in which he is addressing a member of his own party and during which Elizabeth is inadvertently eavesdropping. Mr. Darcy's pride and sefl-sufficient character is developed by his statements about dancing at Meryton ball in general and about dancing with Elizabeth in particular, while Lizzie's ironical (and perhaps slightly narrow-minded) character is developed through her narrated responses to the dialogue she has overheard.
In the inimitable conversations between Lady de Bourgh and Elizabeth, Lady de Bourgh's character is developed as she pronounces regulation upon every facet of life that falls under her purview, which is important because, even though she is only a minor character, her dialogic contributions indirectly further Darcy's character development and do much to escalate the conflict between Elizabeth and Darcy. Elizabeth's charcter development is also furthered by her conversations with Lady de Bourgh as the dialogues (1) cause her dislike of Darcy to become more pridefully and prejudicially entrenched in reaction to her disdain for Lady de Bourgh and, later, (2) cause her to hope that it might not be too late to gain Darcy's love after all--after Elizabeth has had her character awakening revelations and character changes.