on thin ice vs treacherous

on thin ice

adv
  • dangerously, hazardously, delicately 

prep
  • In a dangerous, hazardous, or delicate situation; at risk. 

treacherous

adj
  • Deceitful; inclined to betray. 

  • Unreliable; dangerous. 

  • Exhibiting treachery. 

How often have the words on thin ice and treacherous occurred in a corpus of books? (source: Google Ngram Viewer )