User blog comment:Jho5689/Chapter 392 + and More speculation on Silver/@comment-66.86.223.64-20140711172138

I think that it actually was Deliora, and that Gray suddenly thinks it's his father because as Deliora has been killed, his father's soul suddenly returned for his body's final moments. But, his father isn't supposed to be alive and possessed then, but rather dead with only body possession. I guess it only makes sense for it to really be Gray's father. Now that I think about it, they may have taken his father and made him into a demon the same way they did with Minerva.