Notice that dialect is something that is used to indicate the difference between Leslie and other children in her school. It is clear that she is not from around there and part of her struggle to fit in and be accepted emerges from the different way in which she speaks. This is something that is very difficult for children today who have to go to a different region where they speak with a different dialect.
One of the elements used in this book is regional dialect. When Jesse is narrating, the language is simple and straightforward, being geared for younger readers. However, at times when characters are speaking, the language takes on the regional dialect of Virginia:
"You're the only kid in the whole durnd school who is worth shooting." (Leslie)
Consider the use of the word "durnd" here. Some regions may some "dang", some might say "flipping", others might leave the word out altogether. Paterson is reminding us of where these people are and what type of community it is. Then, when Jesse are Leslie are in the words, they specifically try to use fancier language in order to fit the atmosphere of their kingdom. Jesse actually complains about this:
"He could hardly manage English, much less the poetic language of a king."
However, he does as Leslie asks, and becomes skilled enough at using the "poetic language".
Another element of her writing is her choice of the first person. The story is told through the eyes of 10 year-old Jesse. By putting the story in his words, Paterson allows the reader to become more involved in the story. We see through Jesse's eyes and feel what Jesse feels. Also, since the novel is geared towards a younger audience, the audience feels more connected with the protagonist.