befriend vs keep at arm's length

befriend

verb
  • To favor. 

  • To become a friend of, to make friends with. 

keep at arm's length

verb
  • Avoid a close relationship. 

  • Avoid direct confrontation or struggle. 

  • Keep at a distance, away from one's body. 

How often have the words befriend and keep at arm's length occurred in a corpus of books? (source: Google Ngram Viewer )