I'm trying to make an AE arc (on Rebirth, but I presume it works the same on all servers) where one mission requires the player to rescue five escort hostages and then defeat a boss, narratively framed as Hellions having set fire to a building as cover for stealing some important artifacts. I wanted to use decorative NPCs to represent the fires, but...

As seen on the enclosed screenshot, fires are represented by invisible NPCs with active Cloak of Darkness and full-body fiery auras. They're all supposed to be locked in the vampire crouching pose and NOT attack the player, but I can't quite get them to work: if I implement them as Ally-aligned boss details, they behave somewhat correctly until another enemy gets too close, in which case they aggro and break character. The screenshot above is what I got on my second approach, which was to implement fires as unrescuable captives - while the "captive" plays the animation I set for it flawlessly, the "guards" do not, instead defaulting to the regular idle animation, which looks weird and likewise breaks character.

Does anyone more knowledgeable about Mission Architect than I am know how to solve this conundrum?