User blog comment:PUNCHURPREGNANT/Gray and Silver Predictions/@comment-180.194.244.232-20140430161113

I'm pretty sure he's the future version of Gray... 1. He said, "Natsu for all people," in chapter 368 2. Juvia can feel something strange 3. It is possible that he change his name too Gray 4. Same power. 5. Yes, he is an Ice Demon Slayer something. My theory is that he can plant a lacrima (did i spell that right?) inside his body like Laxus and Cobra (Second Generation) or like what Kyouka did to Minerva. 6. Natsu smelled Silver and said,"Gray," and Silver froze Natsu and said like he doesn't want to hear that name. I was thinking that he hated his old name and changed it (same answer on 3 but has a theory. ;)) 7. He was introduced when he was visiting a grave. Now, this one is tricky. Maybe, he visited his parents grave. The setting was in a snowy place and full of ruins.

That's all but if you guys think why future gray is in a dark guild. Now, that question is really hard.