apprentice vs right-hand person

apprentice

verb
  • To put under the care and supervision of a master, for the purpose of instruction in a trade or business. 

  • To be an apprentice to. 

noun
  • A trainee, especially in a skilled trade. 

  • One who is bound by indentures or by legal agreement to serve a tradesperson, or other person, for a certain time, with a view to learn the art, or trade, in which his master is bound to instruct him. 

right-hand person

How often have the words apprentice and right-hand person occurred in a corpus of books? (source: Google Ngram Viewer )