@BrokenPromise: Definitely not in this case. ^^; There will be a very serious plot, but not like that.
After fairies get a magical girl, they pretty much stick to those duties of tending to their magical girls. They likely have to report on how they're doing, of course.
@HereComesTheSnow: They get made up on contracting with a fairy. Sometimes by the girl, sometimes by the fairy. There's a case of a NET(since she
is a student still) becoming a magical girl and her fairy becoming so frustrated she calls her "Magical Girl Shut-In Chie".
They're pretty set unless the magical girl wants to change it.