Talk:Ruka Souen/@comment-1.155.71.205-20120228094715/@comment-4975807-20120526191605

In the Vampire Knight official fanbook, there's a small diagram showing how Aidou, Kain and Ruka are all related to eachother. Aidou's father, Ruka's mother, and Kain's mother are siblings. Meaning they all have the same grandfather and grandmother on the Aidou branch extending back. That's why Aido has the surname since his father kept the last name, but Ruka and Kain's mothers did not pass on their surname to their children.