As I've mentioned before, I've been paying more attention to other author's third acts in the past year, once I realized that my own needed a lot of work. (Mainly, I needed to make sure they existed!) The third act is usually when the story changes to a different goal for the hero. The original evil is vanquished, or a large portion of it is, and the hero realizes that they're not done yet; they have one final mission to complete. After completing it, they return to their ordinary world wiser. If the story's done really well, the return also wraps up the theme, bringing closure to the problem that opened the book.
I'm especially interested in what I consider nontraditional arcs or third acts. By that, I mean stories in which some (or most) of the arc is emotional or a psychological shift for the main character, or stories in which the hero isn't necessarily the person who vanquishes the evil. The Hero and the Crown fell smack dab into the first of those "nontraditional" arcs.
Since this was my second read of the novel, I wasn't as overwhelmed by the story, and I could dissect it dispassionately as I read it. The novel starts with Aerin's main problem being that she doesn't fit in: she's the witchwoman's daughter but also the king's daughter, granted a role of authority but not respected for it and in many ways feared. And she's very aware of this. Her problem is not a physical one (like, say, needing to destroy the one ring that rules them all). Instead, the physical challenges she faces give Aerin emotional/psychological strength, but tend to exasterbate her problem, making people fear her more.
Despite the fact that she slays a dragon (a very stereotypical climactic fantasy element), it's only the end of the second act. The third act is all about Aerin facing her personal demon (in the form of her uncle who looks so much like her). When she returns with the "elixir" to her homeland, even the physical act of bringing back a magical sword and the Hero's Crown, turning the tide of the battle and saving her homeland, isn't the end of the hero's cycle. She may have physically saved an entire nation, but it's the fact that her battles have taught her to accept herself for who she is that gives her the wisdom to gain the people's acceptance, too.
(I also find it interesting to note that I had very clear memories of the book through the second act from my first read when I was 12, but not the third act. How telling!)
The Hero and the Crown was a very tightly woven novel of character growth explored on multiple levels, with a strong theme. The hero's arc was a complex weave of physical and emotional growth. To contrast, look at any Janet Evanovich Stephanie Plum novel. There's rarely a lot of character growth to Stephanie, and nearly all the arc is explored through escalating physical danger. What I find fascinating is that Stephanie is always rescued and is never her own "hero," yet I never feel cheated by the story conclusion.