...At the end of the story, the boy is disappointed that Prince Humperdinck is not killed or, in any way that he can measure, punished for his deeds. In a traditional fairy tale he most likely would have been. His punishment may have even been one of great artistic irony.
But the ending of THE PRINCESS BRIDE is actually truer to life. Westley is the bigger person. He chooses to let Humperdinck live, believing that the humiliation of his defeat and the undoing of his plans should be punishment enough. Noble and honorable.
Problem is - Humperdinck is a weasel. A shameless lying weasel without conscience. Weasels and bigger persons tend not to understand one another. The bigger person underestimates the depth of the weasel's weasely nature. The weasel does not recognize the bigger person. The concept is outside of their thinking. The weasel recognizes only winning and losing, and will try every dirty trick in the book to be the winner.
In fact, they may be all the more proud of themselves if they do come out on top by means of dirty tricks. They recognize cheating only if they feel it has been done to them. And they assume that everyone would do it to them if given a chance. So the weasel basks in the glow of dirty tricks, because, to the weasel mind, they are evidence of being the more clever; the one who moved faster. Humperdinck will not feel bested. He will feel cheated because he has not come out on top. Cheated of his due. Westley's actions were noble and honorable; but to Humperdinck, they will represent cheating because he, Humperdinck, was supposed to win. Humperdinck will see Westley as the weaker, because he didn't have the sense to do whatever it took to win.
Those who are not weasels would naturally be pleased to ride off with Westley, Buttercup, Inigo and Fezzik. Those who are bigger persons, even if they do not get everything they want, will still feel all right about themselves. Meanwhile weasels shall forever brood, lick their wounds, and dwell on "next time" when they come out on top again.
That's a lot for a kid to understand, especially one who's just been sick in bed. But it's very useful to know, because it is much more real, and it's what makes THE PRINCESS BRIDE a valuable kind of fairy tale romance.
I used to hate it when the bad guy would live in superhero comics. In the beginning, when I was much younger, I kind of understood the moral justification that Scott notes here, or at least, I accepted it. But as I learned more about the comics industry, I understood the "real world" reason why the bad guys always lived: because characters like the Joker, Lex Luthor, Magneto, the Green Goblin and so on are well-known, licensed moneymakers, every bit as much as the heroes they're associated with, who need to be re-used again and again in order to sell toys and DVDs and underwear and stuff.
As a consequence, though, the longer those villains stuck around, the more villainous they became, doing more and more reprehensible things and exponentially adding to their body count. Within the context of the stories, it became harder and harder for the good guys - or more to the point, the writers - to justify letting them live (concerns about vigilante justice aside). Still, Marvel and DC superhero comics are different in that the stories are open-ended by design, not by nature, and no one has green-lighted "The Princess Bride 2: Humperdinck's Revenge" (yet).
Here in the real world, 32 states in the US still practice capital punishment, as well as 58 countries, but in recent years there has been a strong resistance to its use worldwide. "An eye for an eye" comes from a period of time when it was much easier to carry out and get away with (not unlike the setting of Bride), but history shows that all it ever really did was perpetuate an endless cycle of violence. Scott argues, however, that mercy is a concept that's lost on those who are irredeemably bad, like Humperdinck. Indeed, the threat of death is strongly believed by experts to be little of a deterrent to criminals.
This is hard for a kid to grasp, but it's worth remembering that though Bride is a fairy-tale story, not all the characters are purely black and white, like in almost all other fairy tales. Inigo and Fezzik may work for Vizzini, but they're not evil so much as misguided, as we see when they join forces with Westley later on. Westley himself admits to doing ruthless things as the Dread Pirate Roberts, but it was all in the name of finding Buttercup, his true love.
If all we saw of Bride was the story itself, that would be one thing, but the inclusion of the framing scenes with Peter Falk and Fred Savage provides a context to the movie that not only makes it a little more special, but allows for questions the audience itself might ask to be directly addressed - questions like "Why does Humperdinck get away?" It's the rare children's movie that can be appreciated by adults as well, and it's nice to see that over 25 years later, it can still inspire sociological insight.