User blog comment:FairyRaven/Fairy Tail Chapter 356: Tartarus arc - Prologue, Review and Commentary/@comment-1359322-20131018133156/@comment-24039250-20131018181711

The whole Gray and Silver relation could still happen. Here is my reason: Mashima loves to throw sappy moments in FT so I feel that Silver the demon sometime in the past fell in love with a human who then gives birth to their son, Gray. Sometime later Deliora came and did his thing. Silver finds his wife dead and assumes that his son dies as well, giving him the reason to want to create a devil slaying magic even though he is a demon. Overall, he is a demon that despises demons.