The themes in "Babylon Revisited" address the nature of human existence within the context of one's ability to change and transform your life.  Charlie must remain stable and sober, proving to the Peters that he can take care of Honoria.

Charlie tries to convince the Peters that he is now a controlled drinker, one per day, something that is impossible for an alcoholic to be.  Marion has her doubts.

"She looked keenly at him. “I should think you’d have had enough of bars.” “I only stayed a minute. I take one drink every afternoon, and no more.” “Don’t you want a cocktail before dinner?” Lincoln asked. “I take only one drink every afternoon, and I’ve had that.” “I hope you keep to it,” said Marion."  (Fitzgerald)

Staying sober becomes increasingly more difficult when his old friends, Lorraine Quarrles and Duncan Schaeffer bump into Charlie and Honoria.  They want him to join them. They are persistent, showing up drunk at the Peters' and embarrassing Charlie and making Marion sick. 

Charlie is caught between guilt and temptation.  He did not get Honoria back, he feels drawn to his old life, but resists.  It is only a matter of time before Lorraine and Duncan pull him back into a whirl of parties and non-stop drinking.