persecutor vs tough cookie

persecutor

noun
  • A person or thing that persecutes or harasses. 

tough cookie

noun
  • A person who can endure physical or mental hardship; a hardened, strong-willed person. 

  • A hardy, resilient animal or plant. 

  • Something troublesome or difficult to handle. 

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