"All will die,"
"All men die"
The phrase, "memento mori" first appeared during the Ascendancy's war games with other channelers. A man was found in the presence of a rakshasha, a wretched, violent creature that, surprisingly, the man had tamed. Before his death, he uttered the phrase "memento mori" to the Ascendancy. Afterward, a necklace was found on his body. A necklace that the Ascendancy recognized: an hourglass set in an oval charm.
Seeking confirmation of the memory, the Ascendancy returned to Siberia to exhume the body of one of the Atharim that attacked at the Datsan all those long years before he became President of Russia. The charm was the same, but the phrase "memento mori" remained elusive.
Since then, others have appeared at seemingly random places. One followed Soren and Declan in India. Another appeared at the Vaia Plus fundraiser. The United States' Speaker of the House is one.
Finally, Aria showed the Regus of the Atharim the hourglass charm she claimed to have found, but in actuality, was gifted by the Ascendancy as bait. Pondering the charm, the group "di inferi" rose in his mind.
Whatever the di inferi want, their motives remain unknown for now.