User blog comment:Omega natsu2/Chapter 369: The Place Prayers Reach, Predictions./@comment-2214433-20140129011112/@comment-7418318-20140129091108

"Natsu... no, it can't be" makes me feel more like he knows him than the MS line of "Natsu, out of all people".

But either one can still be due to Silver thinking that it was Natsu who freed the Sun Village of his ice, or because of Natsu's reputation.

Come to think of it, the 9DG are supposed to have served Zeref in the past. Couldn't it be that before he went into hiding, Zeref told Silver about a person by the name of Natsu supposedly killing him in the future and that's what Silver is thinking about?