I am playing a Slayer in "Rise of the Drow" Super Module (Adventure Path) and my character and his brother's back drop involves being a slave of type, that was ultimately rescued. Though not privy to all of their background to date, the twins will end up finding out much more with the help of the GM, so let me explain.
Our party has a Dwarf that has in the passed been open to adopting various races that have been rescued, by some of his own race. This has lead him to adopt two Tiefling twin brothers, that were rescued a few years back. Both with their own personalities and some baggage, as they are privy that they were at one point under the tutelage of the Drow (for their own greedy reasons yet to come out).
Well the one I am playing has some anger issues and for this reason has took up the Slayer(Deliverer) Archetype, due to the nightmares and some torture that have stayed with him visa vie the Drow.
As time goes on the twins will learn that they were experiments of the Drow, in which the Drow had summoned demons and give these demons helpless slaves to rape and impregnate. Then they would train and use them for some secret weapons that would be a lot harder to trace directly back to Drow themselves.
I will be adding some more as time goes on but am looking forward to expanding this storyline and using some of the new feats from The Advanced Class Guide such as "Seething Hatred" and eventually "Extreme Prejudice".
For anyone interested the other Party Members are: