avenger vs guardian

avenger

noun
  • One who avenges or vindicates 

  • One who takes vengeance. 

guardian

noun
  • Someone who guards, watches over, or protects. 

  • A superior in a Franciscan monastery. 

  • A person legally responsible for a minor (in loco parentis). 

  • A person legally responsible for an incompetent person. 

  • A major or final enemy; boss. 

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