backstory vs fiction

backstory

noun
  • A fictitious account of a person's history designed to conceal their actual history and motives. 

  • The previous life and experiences of a person, especially a character in a dramatic work, but also a real-life person. 

  • A prequel. 

fiction

noun
  • A verbal or written account that is not based on actual events (often intended to mislead). 

  • Literary type using invented or imaginative writing, instead of real facts, usually written as prose. 

  • A legal fiction. 

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