User blog comment:Omega natsu2/Chapter 369: The Place Prayers Reach, Predictions./@comment-2214433-20140129011112/@comment-24039250-20140130185211

My theory is similar to that of FTGM on the whole Silver's "Natsu out of all people"/"Natsu....no it can't be". I believe that Silver was created by Zeref AFTER he became a kind hearted person and before he went into hiding on Tenrou Island, and told Silver of a boy that he is waiting for to end his life and that boys name is Natsu. It would make sense that Silver was made after Zeref turned into a pacifist since his magic/curse is basically to exterminate his own kind, so I'm thinking that Silver was possibly tasked by Zeref to kill Demons in order to wipe out the darkness that lives within the world. In that time Silver started to like humans and probably fell in love with one, which is why he prefers to stay in his human form.