interlocutor vs protagonist

interlocutor

noun
  • A man in the middle of the line in a minstrel show who questions the end men and acts as leader. 

  • A person who takes part in dialogue or conversation. 

  • A decree of a court. 

  • An interlocutory judgement or sentence. 

protagonist

noun
  • A leading person in a contest; a principal performer. 

  • An advocate or champion of a cause or course of action. 

  • The main character, or one of the main characters, in any story, such as a literary work or drama. 

How often have the words interlocutor and protagonist occurred in a corpus of books? (source: Google Ngram Viewer )