empathy vs mercilessness

empathy

noun
  • Capacity to understand another person's point of view or the result of such understanding. 

  • Identification with or understanding of the thoughts, feelings, or emotional state of another person. 

  • A paranormal ability to psychically read another person's emotions. 

mercilessness

noun
  • The property of being merciless. 

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