Because it was among the first novels he released under his own name, Balzac did not use characters in La Peau de chagrin from previous works.
He did, however, introduce several individuals who resurfaced in later stories.
Most significant of these is Eugène de Rastignac, the older gentleman who tutors Valentin in the vicious ways of high society.
Thirty pages into the writing of his 1834 novel Le Père Goriot, Balzac suddenly crossed out the name he had been using for a character – Massiac – and used Rastignac instead.
The relationship between teacher and student in La Peau de chagrin is mirrored in Le Père Goriot, when the young Rastignac is guided in the ways of social realpolitik by the incognito criminal Vautrin.

Balzac used the character Foedora in three other stories, but eventually wrote her out of them after deciding on other models for social femininity.
In later editions of La Peau de chagrin, he changed the text to name one of the bankers "Taillefer", whom he had introduced in L'Auberge rouge (1831).
He also used the name Horace Bianchon for one of the doctors, thus connecting the book to the famous physician who appears in thirty-one stories in La Comédie humaine.
So vividly had the doctor been rendered that Balzac himself called out for Bianchon while lying on his deathbed.

The use of recurring characters lends Balzac's work a cohesion and atmosphere unlike any other series of novels.
It enables a depth of characterization that goes beyond simple narration or dialogue. "
When the characters reappear", notes the critic Samuel Rogers, "they do not step out of nowhere; they emerge from the privacy of their own lives which, for an interval, we have not been allowed to see."
Although the complexity of these characters' lives inevitably led Balzac to make errors of chronology and consistency, the mistakes are considered minor in the overall scope of the project.
Readers are more often troubled by the sheer number of people in Balzac's world, and feel deprived of important context for the characters.
Detective novelist Arthur Conan Doyle said that he never tried to read Balzac, because he "did not know where to begin".
Because it was among the first novels he released under his own name, Balzac did not use characters in La Peau de chagrin from previous works. He did, however, introduce several individuals who resurfaced in later stories. Most significant of these is Eugène de Rastignac, the older gentleman who tutors Valentin in the vicious ways of high society. Thirty pages into the writing of his 1834 novel Le Père Goriot, Balzac suddenly crossed out the name he had been using for a character – Massiac – and used Rastignac instead. The relationship between teacher and student in La Peau de chagrin is mirrored in Le Père Goriot, when the young Rastignac is guided in the ways of social realpolitik by the incognito criminal Vautrin.
Balzac used the character Foedora in three other stories, but eventually wrote her out of them after deciding on other models for social femininity. In later editions of La Peau de chagrin, he changed the text to name one of the bankers "Taillefer", whom he had introduced in L'Auberge rouge (1831). He also used the name Horace Bianchon for one of the doctors, thus connecting the book to the famous physician who appears in thirty-one stories in La Comédie humaine. So vividly had the doctor been rendered that Balzac himself called out for Bianchon while lying on his deathbed.
The use of recurring characters lends Balzac's work a cohesion and atmosphere unlike any other series of novels. It enables a depth of characterization that goes beyond simple narration or dialogue. "When the characters reappear", notes the critic Samuel Rogers, "they do not step out of nowhere; they emerge from the privacy of their own lives which, for an interval, we have not been allowed to see." Although the complexity of these characters' lives inevitably led Balzac to make errors of chronology and consistency, the mistakes are considered minor in the overall scope of the project. Readers are more often troubled by the sheer number of people in Balzac's world, and feel deprived of important context for the characters. Detective novelist Arthur Conan Doyle said that he never tried to read Balzac, because he "did not know where to begin".
La Peau de chagrin