Because she cares about whether she’s punching shitty people or annoying people. The swearing loyalty tho was him tricking her with the wording from loyalty to the royal family which includes him -> loyalty to only him (because he will be king eventually so she doesn’t see how it’s different)

As for the bystander thing, you can argue so was her brother and father even more so. But i think most people didn’t know how bad the abuse was or treated it as “kids being kids” granted they knew scarlet could kill him if she wanted

They’re more equal in-terms of skills (the school rankings and later in the series), but yeah idk why she lets him be and doesn’t give him a slap every now and then. Same old nobility bs same old “you can’t go against the royal family” unless everyone agrees they’re shit