Leo Orders is a character mentioned in The Heir.
He was born between The One and The Heir, making his age from around six to eighteen, as his mother, Kenna, had died "years ago", as Eadlyn had put it, meaning he couldn't be an infant. As well, another clue is that when May Singer visited the palace in The Heir, she told Eadlyn, "but Leo has a game Friday afternoon..." meaning that he can't really be a small child.
Leo's mother died some years before the beginning of The Heir because of cardiac problems. His father is a simple man, so he didn't want to raise Astra and Leo in the palace, even though America's family offered several times. His family have kept in touch with them and especially their cousins Eadlyn, Ahren, Kaden and Osten, but his sister and Eadlyn are very different girls.
During The Heir, Leo was having a game that May planned on attending on the day before Astra's dance recital.