fiend vs guardian angel

fiend

noun
  • A devil or demon; a malignant or diabolical being; an evil spirit. 

  • An addict or fanatic. 

  • A very evil person. 

verb
  • To yearn; to be desperate (for something). 

guardian angel

noun
  • A tutelary angel watching over a particular person in monotheistic contexts. 

  • A person who watches over another. 

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