User blog comment:SayuriDarling/The Mark of Athena Official Discussion/@comment-142.176.52.15-20121021005839/@comment-76.245.8.194-20121021032035

They were never in Tartarus before. It's a pit that sucks up anyone who gets near it. The reason people think one of them will stay behind is because it sounds like someone needs to close the Doors of Death from the inside.