Others have brought up the fact that Charlotte sits nicely in the protagonist role while Haruto wants to slide back into the shadows.
I haven't read any source materials, but the way the author has laid out the story, it seems like Charlotte and not Haruto was supposed to be the main protagonist. Everything we hear about her birth and childhood is her family trying to protect her from evil queen because the lady knows this infant girl will be a threat to her in the long run.
And she happily gets Haruto as a big brother who does his damndest to give her a rainbows, unicorns, and Card Captor childhood. He's the interloper, saving his sister from the 'thrown into the Spartan baby pit' story that HE got.