fatherness vs stepfather

fatherness

noun
  • The state or quality of being a father. 

stepfather

noun
  • A husband of one's parent distinct from one's biological father 

  • A husband of one's biological mother after her initial marriage to or relationship with one's biological father. 

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