I want Lumine to end up body-swapping someone in-game at some point.
My biggest gripe with Genshin Impact (after the unskippable SLOW dialogues) is that you switching character is a pure gameplay thing and doesn't affect anything inlore, so talking to Amber as Amber does nothing. It's something I routinely butt heads with my friend over because I see it as a complete waste of what would be a fascinating plot point.