Persona:
The fictional voice that a writer adopts to tell a story.

Example:
"You don't know about me, without you have read a book by the name "The Adventures of Tom Sawyer" but that ain't no matter...There was things which he strecherd, but mainly he told the truth. That is nothing. I never seen anybody but lied, one time or another..."
-Adventures of Huckleberry Fin by Mark Twain

Explanation:
Mark twain takes up the persona of a young, and not to intelligent boy. Twain tells the story from the young boys point of view in order to get a certain mocking/ironic tone and humorous mood in the novel. Also to show the growth of a young boy into a mature boy. This novel can be seen as a reflection on Twain's own life, showing the persona is also affected by Twain, and his childhood.