There isn't much to say about the ballerina, since she's pretty flat. (Her character, we mean.)
We know she's beautiful because the Handicapper General forces her to wear a mask. (Um, jealous much?) But mainly, she exists to be someone for Harrison to take as his Empress and smooch on. Well, she does volunteer—and that makes sense, because we get the impression that she's as remarkable a woman as he is a man-boy: she "[sways] like a willow," and is "blindingly beautiful." Unfortunately, we don't get to appreciate her beauty for long: her decision to hook up with Harrison leaves her dead a few minutes later.