An idea for a questline

[Enkidoh]

You mean a 'Tomato Surprise' type scenario? Again we already kind of have that with the DRK Job quest line (big spoiler)

the Job quest trainer 'Fray', is eventually revealed, by the end of the level 50 quest, to actually be you, or rather, your character's dark side, given form by the DRK Job crystal and your character's suppresed frustration and resentment towards how they were treated at the end of ARR's story (thus effectively they're sort of a 'fake WoL'). At first Fray's comments and attitude seemed fine, but as the DRK Job quests progressed, things seemed a little... off. When 'Fray' starts attacking other npcs verbally, when it seemed like Fray was the one talking, the response from the npcs is that you were the one yelling at them, insinuaiting that 'Fray' wasn't even there. And finally, by the level 50 DRK quest, 'Fray' is revealed to be dead all along and his corpse has been simply reanimated by your dark side, 'Esteem' (which is literally an evil you in every way, right down to having your character's face!), who proceeds to attack you, resulting in you having to put Esteem down and defeat it, and ultimately supress your inner darkness.

So again we kind of already have this scenario in the game. It's possible another such storyline might find it's way into the game, espeically with Shadowbringers lauiding us as becoming 'a Warrior of Darkness', but it remains to be seen how that would happen.