hireling vs lap dog

hireling

noun
  • An employee who is hired, often to perform unpleasant tasks with little independence. 

  • Someone who does a job purely for money, rather than out of interest in the work itself. 

  • A horse for hire. 

lap dog

noun
  • A person who behaves in a servile manner, such as a sycophantic employee or a fawning lover. 

  • A small toy dog, kept as household pet, whose light weight and companionable temperament make it both suited and disposed to spend time resting in the comfort of its master's lap; a dog bred to behave in this manner. 

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