User blog comment:FairyRaven/Fairy Tail Chapter 387: Tartarus Arc, Part 4: Father and Son, Review and Commentary/@comment-24467372-20140606101911/@comment-7418318-20140606104506

Regarding Silver: He did make sure that Franmlath wouldn't absorb Natsu (whether intentionally or not), he gave Lisanna something to cover herself, possibly dropped the sword with which Natsu and Lisanna were able to free themselves and now this.

From his first encounter with Natsu and the speed he showed in this chapter, I'm sure he would have been able to freeze at least Natsu, possibly even the entire team before they could react, but he didn't.

That makes it pretty clear that he's not fully (if at all) on the side of the Demons. But I wouldn't want to call him a good guy yet. He might do all this because he still has use for Fairy Tail for some nefarious plan of his to overthrow Mard Geer and become the new Demon King for all we know and pretending to be a nice guy is just his way to manipulate FT into doing what he wants.

We know pretty much nothing about him short of his immense power, so I wouldn't want to judge if he's a good guy pretending to be evil or an evil guy pretending to be good or something in between.