One of the first things we hear about Buttercup is that she is one of the most beautiful women in the world—the twentieth most, to be precise. But the only reason she isn't ranked higher is that she doesn't care about her appearance at all. She's a tomboy who only wants to ride her horse around the countryside. As the narrator asks, "How could someone care if she were the most beautiful woman in the world or not. What difference could it have made if you were only the third most beautiful. Or the sixth?" (1.12). These are Buttercup's sentiments exactly.
More than just being a tomboy, though, Buttercup practically goes out of her way to neglect her appearance: "She hated to wash her face, she loathed the area behind her ears, she was sick of combing her hair and did so as little as possible" (1.12). But no matter how much she neglects appearance, she can't hide the beauty that lies underneath all that dirt.
No, really. Her beauty is so unfaltering that by the time Prince Humperdinck has her in princess training, she has become—undisputedly—the most beautiful woman in the world. Or as the author tells us, "The twenty-one-year-old Princess far surpassed the eighteen-year-old mourner" (5.7). Girl has come into her own look-wise, in other words.
The loss of her lover, Westley, has made the Princess very sad for many years, and the process has taken its toll by putting lines on her face. But all this does is make her face look even more beautiful and distinguished. The book ends up talking so much about Buttercup's beauty, though, that you start to wonder if there's much of a personality behind it.
It takes her quite a while, but Buttercup eventually realizes that she's in love with Westley, a poor servant who works on her family's farm. Buttercup has spent nearly her entire life bossing Westley around, but the guy has never seemed to mind. Buttercup has become so used to this routine that she comes to take Westley's devotion for granted—it's not until the beautiful Countess shows an interest in Westley that Buttercup realizes she might be in danger of losing the boy's affection.
Buttercup ends up tossing and turning in bed all night when she first suspects a romance between Westley and the Countess. As the author tells us, "Buttercup's case [of jealousy] rated a close fourth on the all-time list" (1.144). William Goldman, you see, has a bit of a thing for lists and rankings.
Once things have calmed down and Westley and Buttercup are safely together, Buttercup tries to get Westley to have sex with her. He plays dumb at first (even though he's not a virgin), and Buttercup tells him to let her do everything, saying:
"I have enough knowledge for us both. Of course I should, considering all those classes in lovemaking I took at Royalty School." (10.335)
Yeah, about those lovemaking classes… That's pretty weird, right? But academics aside, here we see Buttercup going after what she wants. It used to be riding horses all the time, now it's to get in Westley's pants—her interest in doing what she wants is the same. Adding to the sort of take-charge element is the fact that this is the moment that eventually leads to the birth of Waverley, Westley and Buttercup's daughter. So Buttercup's taking control over the moment and her future.
As someone who's been praised for her beauty her entire life, Buttercup sometimes has to insist that people treat her like a human being instead of a pretty painting. Even when she and Westley first reunite, she has to order him to stop talking so much about her beauty. She scolds:
"Enough about my beauty," Buttercup said. "Everybody always talks about how beautiful I am. I've got a mind, Westley. Talk about that." (5.1046)
And yes, Buttercup might be jealous and childish for much of this book, but she's also clever and devoted, and these are things that she wishes people valued in her a little more highly.
The one thing that Buttercup insists on (as a person) is that Westley not keep any secrets from her. She says this directly after they first reunite, remarking, "'We must not begin with secrets from each other'" (5.1052). Westley might sometimes try to keep things from her in order not to upset her, but she insists on being treated like an adult and like an equal. The truth is that she constantly has to fight to be heard as a person instead of just seen as a beauty. It's rough, but if anybody can learn to treat her right, it's Westley.