Are characters who appear in multiple separate questlines immune to being killed?

[Fenral]

Suddenly needing a new GC leader would probably be a royal pain to properly put in the story, and upset a good chunk of that GC's members. I'm rather confident that all GC leaders have plot armor.

Actually... there are two GC leaders who do NOT have Plot Armor, and both already have people in place to take over for them. Kinda makes you wonder.

And it's actually a deeper issue, because with how quests work now, appearing in a sidequest means a character can never come to any harm at all.

I have a partial list I threw together for the hell of it, spoilers for almost everything. Read it only if you want to remove all tension from future MS developments.

The list:

Class and Job Quests:
Nanamo
Merlwyb
Raya-O
A-Ruhn

Hard/EX Mode Primals:
Urianger
Lady Iceheart

Crystal Tower:
Biggs
Wedge
Cid

Binding Coil:
Urianger
Alphinaud

Armor rescinded by sidequest (cannot appear elsewhere):
Alisaie
Nero

[Exodus-E]

snip

Also (and to add to that list), it makes you wonder if the Ascians will truly be gone after all, given they're also involved in all EX Mode Primals (and even more directly for Garuda/Titan/Ifrit EX)...

[Fenral]

Also (and to add to that list), it makes you wonder if the Ascians will truly be gone after all, given they're also involved in all EX Mode Primals (and even more directly for Garuda/Titan/Ifrit EX)...

That, too. There's an Ascian in the SMN quests as well, but I don't have any names.

I have a feeling we're bringing ourselves ever closer to The Question That Must Never Be Asked.

[RyuRoots]

Also (and to add to that list), it makes you wonder if the Ascians will truly be gone after all, given they're also involved in all EX Mode Primals (and even more directly for Garuda/Titan/Ifrit EX)...

I don't think that's an issue so much; I think that falls into "this is how it happened" but it was at least before the Ascians were totally defeated. For example, Alisaie mentions in passing in the post-battle T5 cutscene that she doesn't know what destroyed the Allagans. But we of course know the answer after playing through the Crystal Tower raids. So T5 happens as is, and "canonically" took place before the WoL did the CT stuff with Cid and friends. The Ascians in the EX primals fall in a similar category I think.

As for plot armor and cutscenes, there are slight dialogue changes in cutscenes depending on whether you have or haven't done certain quests/joined guilds/which starter city, so I wonder if they could alter cutscenes to account for missing characters, too, in the future.