WoF has a conflicting message and it's something that's always bothered me a little.
tl;dr: though wof touts a theme about not needing special, predestined things like prophecies or fancy lineage to make a lasting and important impact on the world and society, plots and points involving particularly Glory and Thorn frustratingly contradict this message.
It's the same conflicting message that Warriors gets after it's first arc: that predetermined things like bloodline and prophecy *do*, in fact, define you.
I usually try to not let myself get too worked up about children's fiction and the little things in it like this, but this conflict of theme is just so, so frustrating to me.
If you consider the theme of (the first arc) of Wings of Fire to be "you are in control of your own fate; you do not have to be magical or special to change the world" (which is what I personally consider it to be and if anyone's interested I can write about that too), then Book 3 really messes that all up. Book 3/the RainWing trials done by Glory is the biggest thing that comes to mind but I've not read the whole series recently so there may be more.
The fact that Glory obtains queen status by being related to the ancient bloodline of RainWing queens, not by her own skill, prowess, or cleverness, is in such direct conflict with this main theme. If the theme is that you don't need to be special to attain greatness... why make Glory special? Would it not have been much more of an impact if Glory won fairly, or if she was voted in as queen due to her heroic actions on account of saving Kinkajou? I wouldn't even care if she were still related to Grandeur and the original line. It's the fact that the reason given for Grandeur's forfeiture is, "Ah, finally, a member of the bloodline with royal tendencies."
It's just always bothered me.
In the background, too, there's Thorn--a queen with no royal blood. A fresh kingdom. I actually really liked this, except for the fact that it made Sunny a princess, but... oh, well. That can be forgiven. But now there are rumors that Thorn is going to make Smolder her king to...
...Continue the original royal bloodline.
Look, at the end of the day, I get that it's funny dragon fantasy made for middle school kids, but if the main plot of the book is trying to teach you that you don't need special blood to be an important person who makes an impact on the world, then some of the subplots do a shitty job of upholding that.