In this book Alexandre Dumas writes about the legend that the man in the iron mask became the king.
Dauger was not always isolated from the other prisoners. Wealthy and important ones usually had manservants; Fouquet for instance was served by a man called La Riviere. These servants, however, would become as much prisoners as their masters and it was thus difficult to find people willing to volunteer for such an occupation. Since La Riviere was often ill, Saint-Mars applied for permission for Dauger to act as servant for Fouquet. In 1675 Louvois gave permission for such an arrangement on condition that he was only to serve Fouquet while La Riviere was unavailable and that he was not to meet anyone else; for instance, if Fouquet and Lauzun were to meet, Dauger was not to be present.
The fact that the man in the mask served as a valet is an important one. Fouquet was never expected to be released, thus meeting Dauger was no great matter, but Lauzun was expected to be set free eventually and it