Kate Chopin, "Désireé’s Baby" (1893) from Kate Chopin: Complete Novels and Stories:
Currently, Chopin is second only to Twain--and tied with Hawthorne--for most Stories of the Week at five, making this the last of her stories I had left to read. (And right after I read another story of hers. Isn't randomness fun?) And in many ways, this last story is the one that fits in best with our idea of Chopin as a Louisiana regionalist writer interested in domestic issues.
Here's the story: Désireé is a child of mysterious parentage, adopted by the Valmondé family and married by Armand Aubigny, who has the Aubigny habit of falling in love "as if struck by a pistol shot." They marry and have a child--who turns out to be dark-skinned. With this evidence that Désireé isn't totally white, Armand rejects her, and Désireé takes her baby to walk to the Valmondé estate and disappears. In the final moment, we learn from a letter from Armand's mother that she isn't totally white--which means that he isn't totally white either. (So, Armand, just like his dad, fell in love quickly, without really considering race.)
You'll notice I keep saying "isn't totally white" rather than black because Louisiana society historically had a more nuanced view of race than we get later with Plessy v. Ferguson (1896); and that's one historical fact that this story keeps going in the background: it's not just black and white, but black, quadroon, octoroon, yellow, fair, white. So both Désireé and Armand can pass for white without necessarily knowing for certain that they aren't. (And even the ending doesn't really tell us about Désireé, who may still have African heritage.)
If you read for any length of time in the 19th century--and even some in the 20th--this plot will come up: someone's racial makeup exposed by their child. Chopin plays with this convention by noting that, if you will, it takes two to tango; and occasionally rubbing our noses in some markers that may or may not tell us what's going on. For instance, trying to prove that she's white enough, Désireé notes how she's paler than Armand. Normally that would show us the idiocy of thinking that appearance tells us all we need to know about someone; but here, maybe it points to Armand's mixed race background--as well as the idiocy of judging race by sight.
Chopin also nicely leads us through this story by expanding on or summarizing different parts: We hear in detail how Armand is made happy by his marriage, but we only get in summary the story of how he turns unhappy when he "realizes" the truth of Désireé. So we can focus on what Désireé loses more than on the vehicle of that loss.
The ending also opens up a big question: Did Armand know about his past when he married? Did he drive Désireé out as a way to hide his race? Or does he only find out after Désireé has disappeared into the swamp? Or does he still not know? (We can imagine a quasi-Bluebeard ending here, where Armand goes on to marry and reject a series of women because of his own unknown racial background.)