First, Sadie cares about her appearance for example once she wore makeup, furry boots, and furry clothes. Then she found out that fur isn’t good for magic so she went crazy. Second, Carter doesn’t care about his appearance for example he wore pajamas while fighting a monster! Also, Sadie only cares about herself for example she had a servant when they were on a ship the servant asked if she wanted food she said shut up and go away. But, Carter cares about everyone (except her sister) when Zia died (Carters friend) he cried like crazy, but Sadie didn’t care. Also, Sadie thinks ahead, for example when there uncle left and the baboon was guarding the library Sadie brought cheerios to give to the baboon. But, Carter never thinks ahead for example he almost killed himself fighting a monster! And he didn’t even defeat it. There also both risk takers for example they risked their lives to save the world. Also they’re both host of gods. Finally they’re both magicians.
As you can see they’re not very alike. You probably think siblings would be alike but they have been apart for years.