Luckily for Louis Alexandre - and the other illegitimate children - he was legitimised in 1681; thus he was instantly entitled to a court title. The choice fell on the Comte de Toulouse which he would be known at court as. A more ridiculous appointment was given when he was just five years old; he was appointed grand admiral. A year later he could add the title of colonel of his own regiment.
All through his childhood military titles would continue to rain down on the little boy. Consequently, those of maitre-de-camp of a cavalry regiment and Marèchal de France were bestowed on him as well. During the War of the Spanish Succession he was put in command of the French fleet in the Battle of Vélez-Malaga in 1704.
Louis Alexandre would seem to have been destined for a naval career from an early age. He was made Minister of the Navy and thus came to have actual power at court. As a legitimised young man with a promising career ahead of him he was a very eligible bachelor. Charlotte de Lorraine was proposed as a potential bride but Louis XIV resolutely forbid the match. Instead, Louis Alexandre married Marie Victoire de Noailles in a private ceremony in 1723. To avoid stirring the animosity of the Regent this was kept a secret until the Regent's death.
The couple would have a single child: a son, Louis Jean Marie de Bourbon.
Unlike his brother, the Duc du Maine, Louis Alexandre was less interested in the intrigues of court life. However, he still became the focus of attention in 1715 when Louis XIV decided that either the Duc du Maine or the Comte de Toulouse would inherit the throne should every other line die out. There can be little doubt that Louis Alexandre relished the thought of being now officially in the line of succession which is supported by he and his brother's keen interest in the following procedures.
As can be expected the news were met with shock. It did not take long after the death of the Sun King before the codicil was reversed. Given the mood at court - which was decidedly against him and his brother - Louis Alexandre retired to his château of Rambouillet. He had bought the palace in 1706 from the man who would eventually take over as Minister of the Navy.
Louis Alexandre died at Rambouillet on 1 December 1737.