internecine vs mischievous

internecine

adj
  • Mutually destructive; most often applied to warfare. 

  • Characterized by struggle within a group, usually applied to an ethnic or familial relationship. 

mischievous

adj
  • Causing mischief; injurious. 

  • Troublesome, cheeky, badly behaved. 

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