User blog comment:Caporai/Aghanim, the Gatekeeper of the Void/@comment-26567405-20120806002214/@comment-3286233-20120806003928

Actually, Calypso is Kassadin's forgotten brother. But Malzahar only told Calypso that Calypso's brother joined the organization known as Preservers where Kassadin is the leader.

Even Calypso and Kassadin face each other, they won't recognize that they are brothers (due to their transformation by the Void and they haven't seen each other for 10 years).

Only Malzahar holds the truth. (If Calypso dies, Kassadin would be the loss).