In Letter 4, Mr. De Courcey writes to his sister on the subject of some rumors about Lady Susan's character. In this letter, DeCourcey utilizes hyperbole in his description of Lady Susan:
I congratulate you and Mr. Vernon on being about to receive into your family, the most accomplished Coquette in England.
This comment is not intended as an accurate assertion: while, no doubt, Lady Susan is accomplished at flirting, one could hardly know whether or not she is the most accomplished at it in England. Flirting is, after all, a highly subjective art. Mr. De Courcey is, rather, using this hyperbolic statement to emphasize Lady Susan's coquettish skill. Furthermore, it is important to note that in this particular letter, De Courcey gives his opinion on Lady Susan without ever having met her: his opinion of her character, in other words, is entirely founded upon hearsay. In this context, the use of hyperbole goes beyond the simple need to emphasize a certain impression of Lady Susan. This use of hyperbole also informs the reader about critical biases that De Courcey himself holds. He is prejudiced against her before even having met her: this makes his later allegiance with her all the more shocking to his family and to readers.
In Letter 18, written to Lady De Courcey, Mrs. Vernon further emphasizes the good first impression left on her by Frederica—an impression now cemented in her mind over the course of a few days' acquaintance. To get this point across to her mother, Mrs. Vernon again utilizes hyperbole to describe Frederica:
There cannot be a more gentle, affectionate heart, or more obliging manners, when acting without restraint.
There is, obviously, no possible way to know something so highly subjective as whose heart is most generous and affectionate. This exaggerated language is instead used to emphasize the impact that Frederica has had on Mrs. Vernon, in stark contrast to Lady Susan. In fact, in both the language she uses and the biases she exhibits, Mrs. Vernon's opinions of Frederica and Lady Susan are diametrically opposed. Even in her discussion of Frederica's manners, Mrs. Vernon cannot help but comment snidely on Lady Susan's behavior. The phrase "when acting without restraint" seems to signal to the reader that, in Mrs. Vernon's mind, any deficiency in Frederica's manners could be attributed to the deficiencies of her mother. This releases Frederica entirely from responsibility; if she did act badly at any point, Mrs. Vernon might be expected to still blame Lady Susan.
Whatever negative bias Mrs. Vernon maintains against Lady Susan does not extend to Lady Susan's daughter, Frederica Vernon. The disparity between Mrs. Vernon's views of the two women is emphasized upon Mrs. Vernon's first meeting her niece. She utilizes hyperbole to describe her to Lady De Courcey in Letter 17:
They came in when we were at Tea, and I never saw any creature look so frightened in my life as Frederica when she entered the room.
Frederica is undoubtedly not the most "frightened" creature that Mrs. Vernon has ever seen. This hyperbolic language, instead of being literal, takes on an important role in the passage, contrasting the respective demeanor of Lady Susan and her daughter. Note that Lady Susan and Frederica are diametrically opposed, again: while Frederica is shy and frightened, Lady Susan is suave, manipulative, and domineering. Overall, Mrs. Vernon holds a very binary view of these two women, at least based on initial impressions. While these impressions are not necessarily inaccurate, they lack nuance.
This critique of prejudiced initial impressions and subjective retelling is a central theme for Austen, manifesting prominently in most of her later novels—most famously, Pride and Prejudice.
Upon hearing that Reginald and Lady Susan are divided forever, Lady De Courcey pens this joyous, hyperbolic statement in Letter 40, corresponding with her daughter:
This is the most joyful hour [Reginald] has ever given us, since the day of his birth.
Though this statement is bold and hyperbolic, it reflects the true joy and relief Lady De Courcey feels, knowing that her son has not fallen prey to the schemes of Lady Susan. This passage further emphasizes just how much Mrs. Vernon despises Lady Susan, whom she views as somewhat of an adversary. Such sentiments have transferred from Mrs. Vernon to her mother, via their correspondence: this is evidenced by the fact that Lady De Courcey speaks of Reginald and Lady Susan's separation as one would the vanquishing of one's mortal enemy.
Hyperbolic statements, though not meant to be taken literally, can further reveal the priorities and drives of characters: in the above passage, Lady De Courcey's use of hyperbole reveals not only her joys, but her anxieties. In Regency society, a bad marriage was considered social and economic suicide, of a sort: marrying poorly brought shame not only on oneself, but on one's entire family. Consequently, such matters became the business of the family, bringing both joy and pain, as Lady De Courcey exhibits in this passage.
In the following excerpt from Letter 38, written by Mrs. Johnson and addressed to Lady Susan, Mrs. Johnson discusses her first impression of Reginald De Courcey. Much like Lady Susan and Mrs. Vernon, Mrs. Johnson makes use of hyperbole in the description of her first impressions:
I am really delighted with him, he is full as handsome I think as Manwaring, and with such an open goodhumoured Countenance that one cannot help loving him at first sight.— Mr. Johnson and he are the greatest friends in the World.
It is clearly hyperbolic to state that Mr. Johnson and Mr. De Courcey are the "greatest friends in the World," having only met recently. It is more than likely that Mr. Johnson himself would not call De Courcey his greatest friend. This is, rather, indicative of Mrs. Johnson's tendency to exaggerate, as well as her appreciation of De Courcey. Both Mrs. Johnson and Lady Susan share this tendency, a fact which adds credence to their friendship. This letter further reveals similarities between Mrs. Johnson and Lady Susan: both appear insensitive to the feelings of those around them, as is evidenced by the fact that Mrs. Johnson takes the time to write and send Lady Susan an appraisal of De Courcey, who had just written a letter to Lady Susan denouncing his affection for her.