User blog comment:GotMilk5101520/Silver Backstory & Tartarus and the Tower of Heaven/@comment-5303512-20140602202350

Interesting theories, but I don't think that the Tower of Heaven would be like that, let me elaborate what my theory is,

I think that Ultear was in charge of keeping the Magic Council distracted so that Grimoire Heart can search for the "keys to Zeref" by hiring cultists to create the R systems. But then the revolt happened so Ultear had to improvise and brainwashed Jellal to doing "Zeref's work".

As for Silver back story, I have two theories.

Either Silver was always a demon and had a rebellious streak, he met with Ur, had two children Ultear and Gray, but because of Silver being a demon of Zeref and no doubt being a member of Tartarus or they were seeking him to recruit him, he had to leave and for some reason Gray had to be separated from Ur and thus found him his foster parents.

Or

(Something from Diablo Universe)

Silver was fighting a demon and thus the demon possessed him, then he met Ur, had two children Ultear and Gray, then you know the rest.