There's this nice, wellmade mod by SinisterChipmunk:
http://www.fallout3nexus.com/downloads/file.php?id=1944
However, the slaves you buy in that mod are mesmerized. Thus, the 3 phrases they say when you talk to them, sound like they are brainwashed. And their standing animation is a reflection of that too, making them look as if they're drunk.
Now, I think it would be a piece of cake, for someone who knows about mods, to just edit those three dialogue lines so that, for example, instead of a brainless "I live to serve" they say something like an angry "Yeah, as if I have another choice!"; and then to change the standing animation so that it's a normal character standing animation instead of them looking high on drugs?
I have already asked this little favor to the skilled author of this mod. But I'm an eager person, so I ask it here too, in case someone could quickly do that.