Maréchal was a Master Assassin of the French Brotherhood of Assassins. In 1690, Louis-Joseph d'Albert de Luynes and three other Assassins were sent by their Mentor to recruit a skilled epeeist and singer Julie d'Aubigny, but failed due to d'Albert's misogynistic comments.
As an injured d'Albert came back to make his report, Maréchal was the one to write it, trying to find a middle ground between d'Albert's fabricated story, and the accurate accounts of his other companions. Maréchal personally stated that d'Albert was an "ass" and that no more missions of recruitment were to be entrusted to him, as "no porcelain should be entrusted to a baboon".
Eventually, d'Aubigny was persuaded to join the Brotherhood, with Maréchal training her personally to hone her acting skills, despite d'Albert's prior statement that she had no potential as an Assassin.