(right after Luke questions why she followed them into the abandoned factory and why she is dressed the way she is)

sound smug 

"Why do you think? two bitter enemies are finally about to make peace. this is no time for a princess to be sitting at home.

(After King Ingobert VI reveals that Largo the Black Lion is Natalia's true father)

for the direction use shock and disbelieve 

"I-it can't be. Luke this has to be some kind of mistake! right!?"

"I'm going to ask him myself. I can still catch him if i hurry. I refuse to accept this?"