Marquis de Simonon

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. But soon after her arrival at the gathering, Élise learned from her host, the Marquis de Pimôdan, that De Simonon went missing like her other known supporters.

Reference

 * Assassin's Creed: Unity novel