fiend vs foe

fiend

noun

  • A very evil person. 

  • An addict or fanatic. 

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

verb

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

foe

noun

  • An enemy. 

  • A unit of energy equal to 10⁴⁴ joules. 

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