According to a criticism written by Carlos Baker, Lord Byron's "Prisoner of Chillon" was a poem read to F. Scott Fitzgerald as a child, a poem that, most interestingly, befits Charlie Wales:

A kind of change came in my fate,
My keepers grew compassionate,
I know not what had made them so.
They were inured to sights of woe.
And so it was:—my broken chain
With links unfastened did remain
And it was liberty to stride
Along my cell from side to side.
—Byron, "The Prisoner of Chillon''

For, Charlie feels liberated from his old ways with his new success and moderated habits while at the same time, he is still chained to his past.  Truly, Charlie is yet a prisoner to his past because he deludes himself in thinking that he can choose to keep a part of it and not become locked to it.

When Charlie arrives in Paris, the city so much like the amoral, sensuous, decadent place it was when he and the other expatriates lived lives of dissipation and idleness before the Stock Market Crash, he makes the mistake of entering the bar to the Ritz where so many of his nights were spent in the debauched past. Unknowingly, he reattaches his chains to the past as he leaves a note for his one friend remaining in Paris, Duncan Schaeffer. Also, Charlie brings into question his rehabilitation from alcoholism by entering the bar and having a drink, and later, by seeking the nightlife that first evening.

Because his deceased wife is her sister and she is the foster mother of Helen and his child, there is a figurative wall between Marion and Charlie, whom she blames for the death of Helen. Thus, when he visits Marion and her family, Charlie is yet imprisoned by his past, an imprisonment exacerbated by the appearance of Duncan and Lorraine Schaeffer, drunk as in former times.  And, so, the "links unfastened" do remain and Marion changes her mind about allowing Charlie custody of his daughter as he apparently cannot be rid of his past.  As her cousin swings Honoria like a pendulum, this symbolic gesture recalls the lines of Byron's poem as the prisoner "stride[s] from side to side." Fatefully, Charlie is chained to his past and the story ends with Charlie at the Ritz where he has been at the beginning, alone, as he has been locked out from gaining custody of his daughter.  And, even though Charlie knows that "they couldn't make him pay forever," he does realize that his imprisonment of his days are not yet over.