Carve the Mark

Carve the Mark centers around two cultures that live on the same planet. They both think of each as a lesser culture. All the key people in the story have special "powers". One guy cannot feel pain. Another can swap memories with another person. There are many other various powers. One leader leads a kidnapping to attempt to get the "oracle" from the other culture. This causes two families from different cultures to be interrelated. One of the cultures in interrelated in the galaxy, while another tries to be insular. (However, the leaders do speak other languages.) There are all sorts of various conflicts. Sister is upset with brother, and falls for her forced "servant".
I often found myself confused with the many different supporting characters involved. The book wasn't great, but it wasn't horrible either.