avert vs let in

avert

verb
  • To ward off, or prevent, the occurrence or effects of. 

  • To turn aside or away. 

let in

verb
  • To associate with. 

  • To let someone or something come in; to admit someone or something in. 

  • To divulge one's inner thoughts to (someone), making oneself emotionally vulnerable to them; to open up to (someone). 

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