Hello. You did not enter the text to which this question refers, which makes it impossible for it to be answered in a specific way. However, I will try to help you in the best possible way.
It is likely that the author uses the dialect to show someone who is an "outsider," that is, the author may have used the dialect to show a character who does not belong to the place where the story takes place and this affects the history by showing contrasts and diversity. This is because the dialect is the term that represents a different form of language and communication that people from different regions present.
