Lilies on the grave... (HW-spoiler ahead!)

[Ayuhra]

I don't see a point for an ascian to possess a dead body unless they seriously ran out of ideas.

As of the Summoner quests Ascians possessing corpses IS a thing, to be fair. Weaker Ascians (ie Ascian of the Twelfth Chalice etc) don't have the strength to take on still living hosts.

Thus do I pose the question: could it be that the Twelfth Chalice and his black-masked brethren are not as practiced in the art of possession as their red-veiled masters? At the time of the battle, our bodies were the only available hosts nearby. Assuming that he also lacks his superiors' facility to flee to the space betwixt worlds, I suspect that our foe's sudden cowardice stemmed from an inability to force his soul into our living vessels.

Twelfth Chalice had been using a certain dead NPC as a puppet.

Not saying an Ascian will possess Haurchefant but if they wanted to play that card, they have a set up for it.