User blog comment:PUNCHURPREGNANT/Gray and Silver Predictions/@comment-24784846-20140531223452

Now this is just my theory and I thought I would share but I think the Silver and Gray are father and son, and the story behind that was Silver was this all powerful dude in Gray's hometown, and Gray wanted to beat him, he heard of a book that summons a power demon that you could control, unknowing of what could happen, Gray took the book and summoned Deliora and Deliora was unsealed and during the whole destruction stuff, Gray told Silver what he did and Silver was furious and unable to stop Deliora from destroying the town and killing his Gray's mom and almost Silver, and now despises Gray.

I think was Silver was a human but you know how we recently found out that when dragon slayers kill too many dragons they become one so i was think what if a demon slayer killing too many demons becomes one. So that would negate the Future Gray theory, and it would be a good plot twist

Well I do think if anything Deliora HAD to be summoned by someone otherwise that thing would have been roaming around for so long and it would be stupid that no one stopped it.