As we know, Geneviève had already met Louis before the Blakeney party. It was during a trip to Paris that Geneviève attended a Bal des Victimes, a brief fad following the crash and burn of the French Revolution. It became quite fashionable for upper crust young people who had escaped the fate of Mme. Guillotine to wallow morbidly in their good fortune. One way was in fashion. The simple white tunic had been popularized by Marie Antoinette, but it really took off in the late 1790s. On one hand, it resembled the classic peplos worn by women in ancient Greece, and everyone was ancient history crazy at the time. Also, it brought to mind the prisoners being brought to execution in the crude tumbrels, stripped down to their white chemises. To accentuate this, women wore the costume à la victime, with long red ribbons around the neck, and often wrapped across their shoulders and down their arms, to suggest blood. Some women cut their hair short and ragged to complete the effect. The most gruesome touch was the habit of men to jerk their necks while bowing during introductions.
Strange parties were held by and for these folks, most famously at the Hôtel Thellusson. It was a psychologically difficult time for everyone, a phenomenon repeated again and again after devastating societal upheavals. I am reminded of the "Lost Generation" after World War I.
But for Geneviève and Louis, it was the beginning of a lovely romance.