User blog comment:FairyRaven/Fairy Tail Chapter 392: You Must Not Forget, Review and Commentary/@comment-7418318-20140711094725/@comment-7418318-20140711100717

Maybe Silver was brainwashed into believing that he really was Deliora and that was only broken during the fight (probably by that last potentially fatal wound). While it would be somewhat of a repeat of what was done to Jellal, it would still make more sense than Silver doing such terrible things to his son of his own will for no good reason.