Gilda

A cousin of princess Morgan.
Now that Morgan has escaped the palace to become a renowned knight, forfeiting her crown, Gilda and her family have been invited from another country to join the royal court, with her older brother being chosen as the next heir to the throne.
She eventually becomes a friend of Olympia, wanting to help her escape the arranged marriage with her brother, who would only want to marry Olympia to hopefully gain an aesthetic gem core in their children (which would be tangible proof of their royal bloodline ---something that Gilda's brother lacks).