lead character vs mainstay

lead character

noun
  • The main protagonist in a work. 

mainstay

noun
  • A chief support. 

  • Someone or something that can be depended on to make a regular contribution. 

  • A stabilising rope from the top of the mainmast to the bottom of the foremast. 

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