How does Charles come to realize the extreme danger he's placed himself by returning to France at this time?

Charles realizes the extreme danger of returning to France when he witnesses the growing hostility towards outsiders and the escalating violence of the revolution. His initial belief that he could navigate the situation safely is shattered as he encounters the realities of mob rule and the pervasive atmosphere of suspicion. Conversations with locals and the changing political landscape make it clear that his status as a foreigner and potential royalist puts him at great risk. Ultimately, he understands that his decision to return has made him a target in a volatile and unforgiving environment.