Yelena and Sonya
These two ladies are at odds in almost every way. But the biggest way is that Sonya is "plain" while Yelena is beautiful. And in the society they are living in, that's enough to fate Sonya to spinsterhood and Yelena to a life of being chased by men. On their own, they're probably bad enough, but put them together and the differences send them shooting to their respective ends of the spectrum.