*Rolls eyes* I just have a different way of of viewing such things. For people who saw slaves as things, the mind of the slave would have no real value as long as it did what is was suppose to, and in the case of the slave being rare and dangerous, it would have the most value to a collector as safe and easy to show off to others. In the case of your RP, it seems that the rebel leader was still a person in the emperor's mind, not an object, so the parallel can not be drawn. Kings would often try to subjugate counties and lord they conquer, leaving them a bit of their own culture and the like because they are more valuable that way, but in these cased, the lords and people are still seen as humans, not object, like slaves are. That's the only point I was trying to make really is that when it comes to slaves,a true slave collector would never see any real value in the slave's ability to think, only seeing value in owning such a rare piece and more enjoying showing him off than caring what chores he could do. Like those crazy people who buy art without being able to appreciate it. It may be a profound and moving piece, but all they care about is showing it off to their friends and making other jealous.
I personally would never think this way, but as a student of human nature, and someone who strives to make sure he is able to write things I don't believe in accurately I have had to dig into such unpleasant things. :P
EDIT:
Oh, and about Joseph. The soft breaking still requires a potion, however it is a diluted version of the original. However, this does mean that with every generation his bond to the family has be re-affirmed, and even though it was in a much less powerful manner. . .I's like cigarettes. The longer you have been smoking them, the harder it is on your body to quit. As for when he's freed, there will be a couple days where he is sick as a dog, but think of it like a smoker going through withdrawal, but at the end of it his/her lungs are clean and there is no remaining chemicals int here system begging to be fed by nicotine. However, they will still have the off habit of reaching for their pack after a meal, or feel restless son occasion when they have nothing to do with their hands since they no longer are handling a cigarette all the time. Odd little quirks, but no vicious need for the chemical. So, in this case, Joseph's natural loyalty to Alexi and his brother will still be there, if that is part of his free mind, however he will no longer feel the need to submit if given an order by any given human. He may occasionally start to comply before realizing that "Hey, I don't have to, up yers!" His wills till feel the guilt of his actions from long ago, but he will actually be able to get over it now that he is no longer constantly bound to one of the bloodline that he caused harm to. I hope that makes sense. Alexi made very sure that the freeing potion would work quickly, albeit a bit harshly, so that it only takes a couple days for the physical recovery. After that their minds and hearts will be able to heal, no residual feelings of their previous owners keeping them down. Those who have been hard broken and horribly treated will take some time to recover, but with (Hopefully :P) Erik and Joseph's help, and the aid of the resistance under their guidance, recovery will be as painless as one can expect. *Shifty eyes* Despite what's going to be going on at the same time. *Devious look*