User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-3325617-20140704194328/@comment-24502975-20140704235652

Well, they're the 2 Red Dragons in the Apocalypse, so I think Great Red would be the closest to an actual 'rival' in both power and origins (although Great Red doesn't care about anything except swimming in the Dimensional Gap)