In Shirley Jackson's short story "Charles," Laurie's mother narrates her oldest son's experience of going to kindergarten. In the opening scene, his mother describes her son, having declared he would no longer wear corduroy overalls, as leaving behind his toddlerhood sweetness in favor of a more insolent persona. Consider the following quote:
I watched him go off the first morning with the older girl next door, seeing clearly that an era of my life was ended, my sweet-voiced nursery-school tot replaced by a longtrousered, swaggering character who forgot to stop at the corner and wave good-bye to me. He came home the same way, the front door slamming open, his cap on the floor, and the voice suddenly become raucous shouting, "Isn’t anybody here?"
Although subtle, the behaviors of a swaggering child who slams the door, leaves his things on the floor, and shouts an impolite greeting set the stage for the audience's understanding that Laurie is not exactly what his parents believe him to be.
Laurie invents Charles in order to brag about his outrageous behavior at school without the consequences of his parents knowing the truth. His parents become so fascinated with the stories of Charles's terrible behavior, that they don't deal with Laurie's bad behavior. Laurie insults his father, uses bad grammar and manners, and throws his things around carelessly, which is clearly not within the established guidelines of the household. However, the things that Laurie reports that Charles does are so shocking, the parents overlook Laurie's mistakes to focus on the problem of Charles.
For his part, Laurie does offer a clue as to why he (who is the real Charles) does these things. When his parents ask Laurie what he thinks the school will do about Charles, Laurie replies "throw him out of school, I guess." This could be inferred as Laurie's motivation for his in-school shenanigans. His Charles stories certainly gain him a lot of his parents' attention.
At the end of the story, when Laurie's mom finally meets the teacher, she tries to broach the subject of Charles with Laurie's teacher. That is the moment when Laurie's mom finds out Charles was invented by Laurie. The story ends abruptly there, but the author offers us clues that Laurie is Charles when the teacher informs Laurie's mom that "We're all so interested in Laurie." She also praises him for being a good helper, which aligns with Laurie's reports that 'Charles' decided to become a good student. The teacher also hints at "occasional lapses." The reader is struck with the realization that all this could have been avoided with better communication between the parents and the teacher.
As far as what the parents will do, each reader must make their own inference. The author provides sufficient textual evidence that Charles's behavior is unacceptable to them, and that they blame bad parenting for the wayward child's behavior. The irony is that they are the parents. My opinion is that Laurie's parents choose to be in denial over the behavior of their son. Since there is a baby in the house, perhaps Laurie invented Charles as a means to get more attention. Whatever happens next is up to the imagination of the reader. I'd say that Laurie's parents have their work cut out for them once they realize the truth.