"But [i]why[/i] though?"

Chen's why is so many questions. Of course, it's the why of the hero who just doesn't understand the villain's motivation and is supposed to stop them. That's in there with a little tone of defiance. But it's petulant too. It's the why of a frustrated little girl. It's [i]why can't we just hug and snuggle like this?[/i], plus some [i]why can't I just do what I want instead of being stuck having to deal with you?![/i] And if Chen weren't still leaning into Qiu, the other Princess might almost have expected Chen to stamp her foot in frustration the way her body shivers as she asks it. 

Qiu might think that this is her shards at work at first. After all, Chen's used to both her mothers, especially Ysel, so Qiu dropping herself as the single dominant point in Chen's world like this might be pushing her into frustrated daughter mode. But here's an insight that Qiu might have. The way that Chen responded so fast and so honestly, that's not just shards. Chen might be a superb sword duelist and top-tier when it comes to navigating magical puzzles, but she has no conception of being [i]in charge[/i] of anything. She's lived a life of expectations and demands and she [i]doesn't like it.[/i] So her reaction asking why you'd want to conquer everything, that's because she really, honestly doesn't share those desires at all to the point that she can't even get in the headspace of someone else that has them. 

This [i]probably[/i] is not the intended effect of the impressive army. Chen's impressed, sure, but...exasperated might be a better word? She just doesn't get why you're doing all this, and her body language is a bundle of tension. She doesn't stop leaning on Qiu because...well, she doesn't know either, it feels nice and she wants to live in a world where it's okay for her and Qiu to just hug each other and nothing bad will happen, but it's obvious she doesn't believe, in the slightest that's the world she's in now.