I'm writing a story about twin princesses, the younger one is taken away from the castle to prevent her from being killed due to the tradition of the royal family only having one child. The king and queen are, needless to say, arrogant and evil. The older twin who lives in the castle is snobby. The younger twin, who doesn't know she's a princess, grows up a peasant.
There also needs to be a love interest for the snobby princess, who happens to be the peasant princesses best friend.
Time setting: 1500-1650s, somewhere around there. Theme: Serious. No fluffy princess story here!