dark horse vs seeker

dark horse

noun
  • Someone who possesses talents or favorable characteristics that are not known or expected by others. 

  • A candidate for an election who is nominated unexpectedly, without previously having been discussed or considered as a likely choice. 

  • Used other than figuratively or idiomatically: see dark, horse. 

  • A horse whose capabilities are not known. 

seeker

noun
  • One who seeks. 

  • In the sport of Quidditch or Muggle quidditch, a player who attempts to catch the snitch. 

  • Especially, a religious seeker: a pilgrim, or one who aspires to enlightenment or salvation. 

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