Hello, this is the author speaking, not Kara.
I'm here to do some explaining about the changes you WILL see or can expect from Kara and Diana in the future.
First, I want to make it clear that before the twins are Justice maniacs, they are people like us. In the end, sometimes they will make selfish choices. They won't be goody two shoes, nor will they be anti-hero. They don't like killing people, but living in the OP World has desensitized them...a lot.
From their time as an Admiral as well as currently the Twin Monarch, they know what it's like to be powerful. However, they have also seen what happened to Whitebeard. This taught them 2 lessons they have engraved into their hearts.
1. They are not invincible.
Quite the obvious one as there is no 1 dominant figure in the entire One Piece World. They will always have rivals as well as forces that can rival the twins. Since they spent their teenage life as one of the strongest beings in the world, they became a little arrogant and overconfident in their strength...but they know better than anyone else that they are not immortal. After all, they met ?? who was on a different level than anything they've met so far.
2. Old Age
Whitebeard's loss was mostly due to his old age and this frightens both Kara and Diana. They plan to stay here a long time. This means long term planning ahead. I think you can already guess where this is going but for the next few arc, the focus of the twins will be on 'Eternal Youth'. Just like how you would handle very precious information, naturally, they will try to keep this ambition a secret except each other.
I just wanted to give you readers a heads up for what is coming up. Let me say right here but Kara is still the same cute and kind of shy Kara as Diana is still Diana. Their environment and demands of others have shaped and changed them a little bit over the course of a couple years, but at their core, they are the same girls as you saw in the first chapter.
I hope you enjoyed the story so far!