I'm currently working on an Ironborn character by the name of Daeron Irondeep and in his history it mentions how he obtained his three Salt Wives, one was the most beautiful woman in a Summer Island town he raided, the other two were Free City Noble women hoping to sail back to Essos (with many others) after the Ironborn started raiding the region, but their ship was come upon and Daeron claimed them both.
Now all three live in the Port city of Blackcliffs in the Iron Islands. As a Salt Wife they are only a few steps above a slave and all three were almost certainly raped by Daeron during or shortly after they were taken from their friends and family. They will not have the easiest lives, but could be very fun to play with for the right players.