Laurie's parents never make an effort to ascertain the real truth about their son's fictional classmate, Charles. Their complacency stems from their belief that he is telling the truth. Laurie probably realizes that his parents are taken in by his story and that they won't try to establish the truth since there is no reason for them to do so. After all, he is not the one misbehaving. Although his parents are aghast at what Laurie tells them about Charles, they do not make any inquiries, and they wait until the PTA meeting to address the issue. Their apathy gives Charles more opportunity to persist in being disruptive and disrespectful.
For his part, Laurie obviously believes that speaking about Charles absolves him from guilt since he is, indirectly, admitting to his own wrongdoing. His repeated reports about Charles's behavior encourage him to say even more. He is testing the waters and attempting to see how far he can test his parents' patience. His reports indicate that Charles is getting worse, and Laurie clearly wants to see how far he can go before his parents become indignant enough that their child is being exposed to such horrendous behavior.
There are two reasons Laurie's parents took a long time to find out the truth about Charles.
First, they never suspected that Laurie was hiding the truth from them. Both parents believed Laurie's stories about Charles, simply because Laurie never showed any guilt about his embellished narrative. Laurie's stories about Charles also provided a rationale for his shocking overnight transformation. In all, Laurie's parents were probably relieved that their son could provide a reasonable explanation for his puzzling behavior.
Second, Laurie's parents made little effort to verify Laurie's veracity; such was the trust they placed in their young son. Neither parent could envision Laurie as anything but Charles' unwilling victim. In fact, Laurie's mother discovered the truth only after she attended the P.T.A. meeting. She had hoped to see Charles' mother there. However, as the text reveals, she was shockingly disappointed.
So, Laurie's parents took a long time to discover the truth because they trusted Laurie's version of events completely and they failed to confirm their authenticity.
There are several textual clues that can be used to support inferences as to why it took so long for Laurie's parents to discover the truth, but there is no direct statement made in the story that explains it.
The opening paragraph describes Laurie as a sweet-voiced nursery school tot who has turned into a swaggering, belt wearing boy who forgets to say goodbye to his mother. One could infer that one of the reasons the parents are slow to figure out the truth is because they are having difficulty letting go of the image of their sweet young son. They close their eyes to the changes going on in Laurie that go beyond his physical appearance.
The author gives several clues throughout the story that show that Laurie's behavior is similar to Charles's. He shouts raucously on two occasions: once on his first day home from kindergarten, and once the first day Charles has to stay after school. He speaks insolently to his father, saying "Hi pop, ya old dust mop" and telling a joke "Look up, look down, look at my thumb, gee you're dumb." He also spills his baby sister's milk.
But because of the invention of Charles, the parents don't suspect Laurie, they simply think that Charles has been a bad influence on their son.
It is interesting that there is no communication between adults in this situation until the PTA meeting at the conclusion of the story. The teacher doesn't call Laurie's parents to tell of his unruly behavior in school. Laurie's parents don't talk to the teacher or other school personnel about their concerns about Charles. Laurie's mother is desperate to meet Charles's mother at the PTA meeting, but she doesn't make any efforts to try to get in touch with her prior to that meeting.
The invention of Charles appears to be the perfect ruse for Laurie to deflect the truth and consequences for his bad behavior.
In the minds of some parents, their children can do no wrong. To admit that one's child can have a behavior problem is to perhaps admit a failure in one's ability to parent. Maybe the reason that Laurie's parents do not catch on to the fact that their son is describing not a classmate's outrageous behavior, but in fact his own, is that they are willfully blind to Laurie's naughtiness.
Laurie's parents may be taking pleasure in their belief that their superior parenting has produced a son who is not in trouble at school. And the pity that they ostensibly feel for Charles's mother might really be a bit of Schadenfreude. These distractions enable Laurie to keep up the pretense. He is a skillful liar and is able to keep them in the dark for so long because of their willingness to believe in their son's innocence.
In Shirley Jackson's short story, "Charles," Laurie goes off to kindergarten and every day comes home with a new story about a boy named Charles. The reader finds out at the end of the book that Laurie is actually telling stories about himself. So, why does it take his parents so long to realize Laurie IS Charles? One thing for sure is that Laurie is either very smart or very devious (or perhaps both)! He has figured out that by immediately telling his parents tales about a "bad" boy named Charles, the focus would come off Laurie. Laurie tells his Charles' stories so well, his parents forget to ask him about what HE did at school. All of their conversations center on Charles, and Laurie is very believable. How many parents would automatically assume their child was the "bad boy" in class, especially when their child is such a great storyteller?