The devil would cleverly disguise himelf as a messenger of light, i.e. minister of some kind, and who would suspect someone talking the walk? I'm not suggesting the Bible is anything but God's word, but people can be delusioned into thinking that after some study and even knowing the Bible well, that they are no longer who they once were. I'm no angel myself, fallen or otherwise, but you know what I mean? John Doe has the point -- sometimes you have to look at yourself, or your behavior as the enemy, and go from there.
The WT website has an article on angels, and it finally mentions protective guardians at the end, so as to accept their existence I guess. They can also help Jehovah's chosen ones defeat their enemies.
In conclusion, I decided the person (who is no Witness) poses a defensive position. I figure to just stay far away as possible from her, and all those demons as well.