In “Désirée’s Baby,” Chopin relies on dramatic irony that intensifies as the story moves toward its resolution. Dramatic irony occurs when readers suspect or know for certain something that the characters do not. It can serve as a comedic technique, or, as in the case of “Désirée’s Baby,” a tragic one.

The driver of dramatic irony in the story is the lack of knowledge about Désirée’s and Armand’s pasts. In her case, no one knows where she came from, so the assumption that one of her parents was Black is easy to make and impossible to disprove. This concerns Monsieur Valmondé before the wedding. He goes so far as to warn Armand about “the girl’s obscure origins.” In the culture of the story, a young man of wealth and land needs to make a favorable marriage that will enhance the fortunes of both families. Proudly and impetuously, Armand ignores this convention as his passion “drives headlong over all obstacles,” creating suspense; the inclusion of this detail suggests there is to be some revelation about Désirée’s ancestry by story's end. This sense of foreboding comes to fruition when it becomes clear that Désirée’s son and La Blanche’s son could be, and may be, half-brothers.

For most of the story, readers may believe that Armand is correct that his wife and child are not white. But in a final twist, readers learn the truth alongside Armand: his mother was Black—and relieved, apparently, that Armand had no reason, as he grew into a man, to know it. This revelation resolves the story’s dramatic irony and releases much of its tension by placing the responsibility for Désirée’s death, and her son’s, squarely on Armand.