extort vs repay

extort

verb
  • To take or seize from an unwilling person by physical force, menace, duress, torture, or any undue or illegal exercise of power or ingenuity. 

  • To obtain by means of the offense of extortion. 

  • To twist outwards. 

repay

verb
  • Synonym of pay back in all senses. 

  • To make worthwhile; to yield a result worth the effort. 

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