The Marquis de Simonon was a member of the Templar Order, known to be loyal to the de la Serre family, even after the murder of François de la Serre.
In October 1789, he was expected to come to the Templar meeting ordered by Élise de la Serre, to pledge his loyalty to her and support her claim as the new Grand Master. Soon after her arrival at the gathering however, the Marquis de Pimôdan told Élise that de Simonon had gone missing like her other known supporters. Pimôdan did not specify if as him, Simonon had been pushed to betray the De la Serres by fear for his life, if he was hiding as Chrétien Lafrenière, or if he was simply killed.