When the children of the imperial family were 7 years old. That is the right time to introduce them to each other. The purpose is to build a big connection between families. So when they grow up. They can help each other to keep this country safe.
As far as we know. There are only two children of the emperor that already get married and have children. The first child of the emperor is the imperial crown prince, Sam. Prince Sam is married and has one son. While the second child of the emperor, Raphael. He married then has one son and one daughter.
"His name is Victor. Maybe he was a half-vampire. But he is your little brother and uncle of Vanessa-and-so to Basil."
At the same age as me, Victor is adopted by the Emperor to be his son. Of course, we welcomed him with great affection. Despite having no blood relationship and he's a half-vampire. He and I are good friends with a connection as niece and uncle.