indulgence vs mercilessness

indulgence

verb
  • to provide with an indulgence 

noun
  • An indulgent act; a favour granted; gratification. 

  • A pardon or release from the expectation of punishment in purgatory, after the sinner has been granted absolution. 

  • The act of catering to someone's every desire. 

  • The act of indulging. 

  • Tolerance. 

  • A wish or whim satisfied. 

  • Something in which someone indulges. 

mercilessness

noun
  • The property of being merciless. 

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