Light spoilers for FF16
The Undying are by far the worst part about FF16's story in my opinion. Not only do they die, but they seem to not care about dying all that much at all. They have an allegiance to the Phoenix, but they sure do spend a lot of time getting themselves killed doing stuff that Clive has to pick up the pieces from. They have this weird, Reddit-tier "coexist" mentality too. There's a late-game quest that has this whole theme of giving people the liberty to die how they want to even if it is not a good death and it was just making me cringe the whole time. This Undying member sacrifices himself to a monster so that a bunch of people can come suicide, effectively, because they believe it will bring them salvation. What a fucking weenie.
Everything else is so good but the Undying leave a very sour taste in my mouth. They're supposed to be on your side, this cool secret order that helps you from the shadows. They really feel like a completely separate entity that just happens to loosely kind of do things that help you because it's their duty, or whatever. They don't have any real conviction and will, which are core themes of the story. Their alignment is neutral stupid.