User blog comment:Rfx9416/Theory: Eustass D. Kidd/@comment-1876594-20141124190840

Since nobody knows if Kid is a D., the anime can not give you hints about that, unless you think that someone in TOEI is a time traveler. Once that only the first point of your theory is still valid, we can argue that to smile when a world noble is attacked is too much common. You you're right, than all the fishmen that tried to kill Mjosgard would have that D. in their names.