Louis de Bourbon rarely followed in his father's footsteps. He never showed an interest in politics and lacked the natural authority which the Sun King was so notorious for. However, in two particular aspects the apple certainly did not fall far from the tree.
Firstly, once he became a widower, Louis married his mistress (Mademoiselle de Choin) but kept the union secret. Similarly, it was widely believed that Louis XIV had married his own mistress, Madame de Maintenon.
Secondly, the Grand Dauphin fathered several illegitimate children - although not nearly as many as his august father. Surprisingly, the "natural" children of the heir to throne never took their place at court and lived rather anonymous lives.
The Secret Marriage
The morganatic marriage with Marie Émilie de Joly de Choin allegedly took place in 1695. At the time of the marriage, Mademoiselle de Choin was apparently already pregnant. Some months following the ceremony she gave birth in secret to a son. He never received a name and was quickly despatched to a trusted nurse in the countryside. Sadly, he died at the age of just two - still having never been given an official name and as such was not publicly recognised.
Their union does not appear to have produced more off-spring. This is a bit odd considering that Mademoiselle de Choin was only 24 years old at the time of their marriage. It could be that Marie Émilie was not particularly fertile or perhaps she had miscarriages that were not recorded. This could very well be a possibility since she lived her life at court in remarkable isolation.
The "Other Women"
Despite his steady relationship with Mademoiselle de Choin, the Grand Dauphin still took mistresses after their union. In the very same year that he remarried, he still had another mistress. Unlike Marie Émilie, she was from a prominent, aristocratic family: Marie Anne Caumont de La Force. Their relationship stretched back to when the Grande Dauphine was still alive - to the great irritation of the neglected Bavarian princess.
Although Marie Anne did not become pregnant until after the death of her lover's wife, Louis XIV still refused to sanction a public recognition of the child. That child was a girl and given the name Louise Émilie de Vautedard. The lack of official recognition placed Louise Émilie in a social limbo. She could not be given a place at court and definitely not a household of her own. However, it would not do either to let her live completely in destitution.
As she grew up, some courtiers eyed an opportunity for securing future favour with the heir to the throne. While the "proper" aristocratic families were hesitant to welcome Louise Émilie into their family, others had fewer scruples. Nicolas Mesnager was from a wealthy family which had earned its fortune through trade. He eventually changed career and became a diplomat. As such, he was a fine match for the illegitimate daughter. His status was not high enough to offend the established nobility but just high enough for it to be a dignified union. The husband of Louise Émilie was no less than 46 years older than her.
The illegitimate line through Louise Émilie would not last long. She died at the age of 25 years and never had children.
As if the relationships with Mademoiselle de Choin and Marie Anne were not enough to occupy his years in the early 1690's, the Grand Dauphin had yet another mistress in this time frame. Françoise Pitel was an actress who had already had eight children by the time she became the mistress of Louis. However, these were fathered by her husband and not by the Grand Dauphin.
Louis and Françoise had three daughters over the years from 1693 to 1695. The first-born was known simply as Mademoiselle de Fleury but she died in her infancy. The second daughter was given the name Anne-Louise. She did survive infancy but only reached the age of 21 years old. Still, she managed to make an advantageous marriage to the Marquis d'Avaugour.
Their final daughter was baptized Charlotte. Of all the Grand Dauphin's illegitimate children, she was the only one who lived past her twenties. She was married to Gérard Michel de La Jonchère, royal councillor. However, the choice of her husband turned out to be unfortunate. By 1723, he was publicly disgraced when it was discovered that he had embezzled public funds. He was put in the Bastille until 1728 and lived a rather drawn-back life following that. Curiously, he died the same year as Charlotte (1750) despite being 20 years her senior. Charlotte does not appear to have had children either.
None of the daughters of the Grand Dauphin were depicted in portraits or the like.