User blog comment:FairyRaven/Fairy Tail Chapter 356: Tartarus arc - Prologue, Review and Commentary/@comment-82.20.156.238-20131020073039

I have a theory or two on Silver and his origins. I don't know if anyone else has thought of it and it may seem a little bit farfetched but I'm just going to throw it out there. I know this chapter said that all of the Nine Demon Gates are some of the strongest demons from the Book(s) of Zeref but I still don't believe Silver is a demon directly from the Book of Zeref.

We know that there 3 types of Slayer Magic: Dragon, God and Demon. OK, now forget about God Slayers for a second we hardly know anything about them or where their magic even came from after they were introduced a good million or so chapters ago (and I think it's artificial anyways). Let's concentrate on Demons and Dragons.

Apparently, when a dragon slayer continuously defeats and bathes in the blood of dragons, they adopt draconic features becoming more dragon-like until they eventually transform into a dragon completely (eg. Acnologia). We also know that this specific transformation (don't know about any other dragon transformations) was aided by Zeref who is basically the Dark Messiah in Fairy Tail. (On a side note, we know that dragon slayers have a special ability/mode that enhances their power: Dragon Force.) Now we know that Zeref has many books focusing solely on his magic (what a prolific authour) such as Living Magic and Death Magic and he practically created the Bible on the Black Arts. What if Zeref, after seeing Dragon Slayers being created by Dragons, decided to create Demon Slaying Magic ((the polar opposite to Demon Creation Magic) which could have happened during the Dragon Civil War or afterwards in Zeref's days of peace) using the foundations of Dragon Slaying Magic. So, there you go, the creation of Demon Slaying Magic which Zeref probably left in one of his books somewhere.

Now, as with Dragon Slayers and their magic, Demon Slayers get stronger with every Demon that they kill. However, also like Dragon Slayers and their magic, the consummation of the Demons' souls (Demon Slayer equivalent of bathing in the blood of a dragon) will slowly corrupt them, turning them into demons themselves (possibly based on those from the Book of Zeref - an unintended side effect) - you know... he who fights monsters and all that. Furthermore, like Dragon Force, Demon Slayers also have their own power-enhancing ability: Demon Force/Mode/Transformation etc. (like a Satan Soul of sorts)

So, what I am basically trying to say is... Silver was originally a human (as Acnologia once was) but because of his Demon Slaying Magic and absorbing Demon Souls he was corrupted and became a Demon or is slowly becoming one, representing one from the Book of Zeref. He can switch between the two forms - Human and Demon - but prefers his Human side because it reminds him of his humanity and past life...

Now why you say? I don't know how but I can assure you Silver is related to Gray somehow. (I personally thought he was Gray's uncle but I'm opening up more and more to the father theory even though we saw his parents' graves). Silver learnt Demon Slaying Magic originally to avenge his family or some shit like that. Whatever, he's badass and part of the Fullbuster bloodline because there are too many things that point in that general direction.

Sorry for the essay and I wrote this while half asleep so I may have missed a few things out as it feels like I'm forgetting a few things.