NPC AI RE: AOE effects

Why, precisely, in any universe, should NPCs just stand like idiots in AOE effects.

I have spent over an hour trying to complete the level 60 RDM quest on Very Easy, and every time I try it, the moron NPC stands in some AOE or another while I'm doing mechanics, and gets themselves killed, failing the quest for me. This isn't a one-off thing, they're programmed to not care about AOE circles, it's completely impossible that this kind of behaviour isn't intended for some sadistic, player-hating reason. Why the hell should I tolerate this kind of behavior from an NPC when I would blacklist a player and leave a dungeon if I saw them doing the same thing?

There are several mechanics in that fight that it sounds like you may not be executing properly if she's dying every time. There are non-stack AoE attacks targeting the player needs to make sure don't hit her or she will take too much damage, so the player needs to keep away from her at all times only moving in close for things like the safe zone for the room-wide AoE section or for his move Black Blood which needs to be stacked with her. These AoE are the player's responsibility to place safely, not hers to move out of. E.g. Keep the boss pointed away from her as much as possible to avoid cleaving her with the column AoE named Brand. She will get a debuff and take a lot of damage on his next move if she gets hit by it since you likely won't be able to cure her to 100% to remove the debuff. You also periodically get large circle AoEs appearing at your feet, especially near the end, and you need to keep your distance from her or she will get hit. When the area is covered in AoE make sure to kill one of the voidfire to create a safe zone. Ideally kill the one whose AoE she is already standing in, but she will move to a safe zone for this move if you kill a different one.

tl;dr version: Focus on making sure you're not putting any orange ground AoE near her and you should pass it easily. Move close to her for Black Blood and keep a moderate distance from her otherwise.