Its not as if angels do not have a free will, they have not been exposed to an opposite view to the extent that we have been, but they are beings with free will because the fall of Satan indicates that.
So here is the question; how do angels differ from humans. They are not corporeal, but they can become corporeal for a time. They can fall, but all indications point to no ability to be reconciled to God once they fall. I am interested in what others may have discovered or think about this. Scripture verses are encouraged as well.
"It was revealed to them that they were serving not themselves but you, in the things that have now been announced to you through those who preached the good news to you by the Holy Spirit sent from heaven, things into which angels long to look." 1 Peter 1:12
"And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
And prevailed not; neither was their place found any more in heaven.
And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him." Revelation 12:7-9