Lady Susan is a first-person narrative, told in epistolary format. To emphasize points of characterization and plot, Austen strategically places her letters in sequence, each reflecting on or providing new perspectives on information revealed in the previous letter. The choice to style her novella in this format provides Austen the opportunity to frequently shift perspectives in a dramatic fashion, altering the reader's viewpoint on a situation over the course of only a few paragraphs. This rapid transition between points of view typically does not occur in traditional narratives, wherein the narrator will pad scenes of dialogue with commentary and observation, ranging anywhere from neutral to derisive in tone. Such rapid shifts in perspective facilitate an increase in suspense or apprehension.
Another characteristic of the epistolary style is the lack of a narrator. No part of the narrative of Lady Susan—except, of course, the short conclusion—takes place outside of written letters. As a consequence of this stylistic choice, the reader may feel unable to discern any objective truth in relation to the plot. Austen's choice to use the epistolary style for Lady Susan aligns with a theme she explores in later novels: that singular perspectives, both in art and life, are inherently unreliable.