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Armor rescinded by sidequest (cannot appear elsewhere):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