User blog comment:FairyRaven/Fairy Tail Chapter 348: Return of the Demon, Review and Commentary/@comment-5598380-20130823103812/@comment-7418318-20130823134355

Considering that the little puff of smoke Natsu managed to conjure wouldn't even inconvenience the demon guy it's hardly surprising he'd flee.

Gray on the other hand managed to have some effect on the demon guy, so either he hasn't yet noticed how hopeless the situation is, or he actually does have a chance.