dark horse vs solicitant

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. 

solicitant

noun
  • One who solicits. 

  • A priest who abused the confessional to solicit women. 

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