become vs forthcome

become

verb
  • To come about; happen; come into being; arise. 

  • To be proper for; to beseem. 

  • Of an adornment, piece of clothing etc.: to look attractive on (someone). 

  • begin to be; turn into. 

forthcome

verb
  • To come forth. 

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