In Chapter 4, Byron tells Hightower about Brown's testimony to the sheriff, including his accusation that Christmas has Black ancestry. Brown uses verbal irony to insult the townspeople for failing to realize the Christmas is Black, but his accusation reveals an important situational irony:
‘You’re so smart,’ he says. ‘The folks in this town is so smart. Fooled for three years. Calling him a foreigner for three years, when soon as I watched him three days I knew he wasn’t no more a foreigner than I am. I knew before he even told me himself.’ And them watching him now, and looking now and then at one another.
Brown is trying to distract the sheriff and townspeople from the fact that he waited several hours before reporting the fire at Joanna's house. He uses Christmas's ambiguous racial background to whip everyone into a frenzy even greater than that over his own poor citizenship. Most of the White people in Jefferson believe that there are fundamental differences between Black people and White people. By using verbal irony, calling the townspeople "smart" when he really means the opposite, Brown pokes at their own racist insecurities about being able to identify Black people in their midst. He invites them to worry not only about Christmas, but also about where they went wrong in failing to notice the man's Blackness. Brown noticed, so why weren't they smart enough to notice?
Brown's accusation and the townspeople's reaction reveals that, ironically, White supremacy makes Blackness important and even coveted by the townspeople. Neither Brown, nor Christmas, nor most of the townspeople has a true sense of belonging in Jefferson. They all have their own stories that alienate them from their neighbors. Still, everyone in town has been calling Christmas a "foreigner" and freezing him out for the three years since his arrival. They see his slightly dark skin as evidence that he might be from Eastern Europe, Mexico, or somewhere else distant to them. Wherever he is from, they think he has even less in common with them than their other neighbors do. Brown, however, was quickly able to see that "he wasn't no more a foreigner than I am." Noticing Christmas's Blackness is the very thing that makes Brown see him as not a foreigner, but rather as a Southerner. Ironically, once the townspeople too learn that Christmas might be Black, they want a closer relationship with him—even if that relationship is one of violence and vitriol.
In Chapter 6, Christmas flashes back to his early childhood at the orphanage and his adoption by McEachern. The chapter ends on a note of situational irony, as the matron tells McEachern that he is free to change the child's name:
They were in the matron’s office; he standing motionless, not looking at the stranger’s eyes which he could feel upon him, waiting for the stranger to say what his eyes were thinking. Then it came: “Christmas. A heathenish name. Sacrilege. I will change that.”
“That will be your legal right,” the matron said. “We are not interested in what they are called, but in how they are treated.”
The matron claims that the orphanage is interested in how the children they adopt out are treated. The implication is that the orphanage wants to protect children from abuse. In theory, this is one of the reasons why orphanages were first established. Society began to understand that children were vulnerable and that not all of them had caregivers who could support them. Orphanages were supposed to be a social service to address this problem. However, it is ironic that the matron would care about Christmas's treatment now, after allowing Hines and the Dietician to mistreat him his whole life. Furthermore, McEachern turns out to be horribly abusive. The orphanage clearly does not have a thorough vetting process for adoptive parents.
Even the idea that respect for a child's name is irrelevant to how they are treated is ironic, especially for an orphan with unknown parents. At the age of five, Christmas has already developed a sense of shame about who he is and where he comes from. The question of his identity will plague him his entire life, and it will eventually lead to his brutal murder. The matron either does not understand that a child's name matters, or she does not care. In either case, her response to McEachern demonstrates that the orphanage is far more interested in appearing to have an interest in children's well-being than in actually protecting their rights.
Faulkner uses dramatic irony and perspective shifts as a motif in the novel, often circling back to the same event from multiple characters' perspectives. For example, in Chapter 13, the boy who drove Christmas away from Joanna's burning house recounts his own version of events:
The boy believed that he was about to be robbed and even killed, and he told how he was about to trick the man into permitting him to drive right up into his own front yard, where he intended to stop the car and spring out and shout for help, but that the man suspected something and forced him to stop the car and let him out.
The reader has already heard this story from Christmas's perspective. Christmas waved down the passing car and asked for a ride. The boy and girl in the front seat started acting strange and refusing to stop the car, so Christmas bailed out. Only afterwards did he realize he had been brandishing a gun. He did not mean to threaten the young couple at all; he only wanted a ride and was too distraught to realize how he came off.
The boy truly seems to believe that his life was in danger. It is hard to blame him for this fear, given that Christmas had a gun and was clearly agitated. The boy is not lying in the slightest. Still, the sheriff and townspeople absorb his subjective version of the truth as the objective truth. The reader, who knows another subjective truth, can see that objective events are being accidentally distorted.
As a modernist writer, Faulkner was interested in how he could experiment with storytelling to best represent life in rural Mississippi. The retelling of the same moments from different perspectives helps him offer his readers a more complete sense of all his characters' reality than is possible with a single telling. At the same time, there is a chasm between what he can offer his readers and what the characters are able to experience. One of the tragedies of the novel is that while the reader can see how and why events play out the way they do, most of the characters are caught in their own distorted versions of the truth. They are thus doomed to misunderstand one another and descend into unnecessary conflict.
In Chapter 15, a group of men in Mottstown brings Mr. Hines home after he recognizes Joe Christmas and calls for him to be lynched. The scene ends on a note of dramatic irony and foreshadowing when Mrs. Hines asks her husband about "Milly's baby":
Eupheus. You listen to me. You got to listen to me. I aint worried you before. In thirty years I aint worried you. But now I am going to. I am going to know and you got to tell me. What did you do with Milly’s baby?
True to the Gothic genre, Light in August features an orphan, Joe Christmas. Questions have swirled around Christmas's racial heritage his entire life. On the one hand, whether or not he is Black changes nothing about the actual events of the novel. On the other hand, much of Christmas's behavior is driven by the belief, by him and others, that he is Black and that his Blackness makes him violent. When Mrs. Hines asks Mr. Hines, "What did you do with Milly's baby?" the reader finally gets a partial clue as to who Christmas's parents are. Mrs. Hines is clearly also learning information she has been missing for 30 years, since Christmas was a baby.
Faulkner immediately cuts to a different scene, refusing to reveal everything right at this moment. The cliffhanger of a question not only amplifies the dramatic irony and suspense, but it also foreshadows the revelatory scene that usually takes place near the end of a Gothic novel. Soon, several of the characters will confess to one another all the information they have secretly been holding onto for years. By playing with the conventions of the literary genre he is using, Faulkner further highlights the fact that all of his characters are caught in a fictional story. They are all subject to tropes and patterns that were established long before they came along. Far from trivializing the novel as a representation of Southern culture, Faulkner's emphasis on its literariness helps the reader see how cultural stories direct the course of people's lives. Christmas's actual identity is in some senses less important than his and others' assumptions about who he is and what that means.
In Chapter 18, the townspeople gather beneath the portico in the square while the Grand Jury decides Joe Christmas's fate. Faulkner uses a simile as he comments on the situational irony of the townspeople's gawking:
[...][C]ountrymen in overalls moved, with almost the air of monks in a cloister, speaking quietly among themselves of money and crops, looking quietly now and then upward at the ceiling beyond which the Grand Jury was preparing behind locked doors to take the life of a man whom few of them had ever seen to know, for having taken the life of a woman whom even fewer of them had known to see.
Faulkner compares the working class townspeople to "monks in a cloister." Like many of Faulkner's imaginative similes, this comparison takes a bit of untangling. Monks are religious devotees who often spend their lives in monasteries, shut away from the secular world so that they can contemplate God. A cloister is an architectural fixture at the center of many monasteries. Consisting of walkways along the inner walls of an enclosed quadrangle or yard, the cloister is a place where monks can commune with one another and with God while also remaining separate from the outside world. The "countrymen in overalls" gather beneath the courtroom like monks in a cloister, but instead of talking about God they talk about their own "money and crops." For better or worse, these townspeople's interests are limited in much the same way that monks' interests might be said to be limited by the walls of the cloister.
Faulkner goes on to describe how, as the townspeople talk about money and crops, they are all waiting eagerly to find out what will happen in the courtroom. They look up to it almost as monks in a cloister might look up to heaven. It is ironic, Faulkner suggests, that they are so deeply invested in the verdict of the Grand Jury when they have always treated Joe Christmas and Joanna Burden as outsiders whose affairs do not belong within their "cloister." By highlighting the situational irony, Faulkner helps the reader see that the townspeople do not care about Christmas and Joanna so much as they care about their tawdry romance and murder plot. They want to know how Christmas will be punished for his taboo, possibly interracial relationship with an unmarried woman. Whereas monks look up to God, the "countrymen in overalls" look up to a justice system that punishes people for breaking race and gender codes.