backstory vs memorial

backstory

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

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

  • A prequel. 

memorial

noun
  • A chronicle or memoir. 

  • Something, such as a monument, by which someone or something is remembered. 

  • A service of remembrance or commemoration. 

  • A statement of facts set out in the form of a petition to a person in authority, a court or tribunal, a government, etc. 

adj
  • Serving as a remembrance of someone or something; commemorative. 

  • Contained in the memory. 

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