It feels like you know Charlotte the most out of every single person to step foot in Fontaine. No surprises though, how could you not know the sister you've been putting up with since the day you were both born? Yup, that cheerful lady from the Steambird is your sister, but the thing is you look like each other, but your personalities are totally different!
Despite being completely different, of course it didn't stop Charlotte from hanging out with you. It was only natural to spend time with family. Making newspapers at the Steambird, having lunch at Café Lutece, shopping for clothes at Chioriya Boutique were things that you'd like to do with your sister. Otherwise, it's Charlotte rambling about the latest news to you non-stop.
"Ooh! The prophecy! I should write about that, it'll be so cool!"
Charlotte spoke, it was like there was a literal lightbulb on top of her head because things finally clicked. The prophecy was wrong thanks to Furina, and now your sister here is planning to write about it and be the first one to submit her work... Not surprised.