fiend vs maniac

fiend

noun
  • An addict or fanatic. 

  • A very evil person. 

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

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

maniac

noun
  • A fanatic, a person with an obsession. 

  • An insane person, especially one who suffers from a mania. 

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