indulgent vs merciless

indulgent

adj
  • Disposed or prone to indulge, humor, gratify, or yield to one's own or another's desires, etc., or to be compliant, lenient, or forbearing; 

merciless

adj
  • Showing no mercy; cruel and pitiless. 

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