An antonym for "author's purpose" could be "reader's interpretation." While the author's purpose refers to the intention behind a piece of writing, the reader's interpretation focuses on the individual understanding and meaning derived by the reader, which may differ from the author's original intent.
athours
Justin Bieber did not make Arthur's Christmas. He sang the song Santa Claus is Comin' to Town for the theme song
An Author's income is based on the quality of their writing, which in turn affects their sales. Although a full-time author might suffer if that person takes too long to write a book, some authors can spend 50+ hours working on their material in any particular week