This "He’s not one of my kids. No. But he’s mine.", gives me a slight bit of hope that Sam isn't a social sadist as well (as the more acceptable) sexual one. At one point my four children were all under the age of six, so I understand how exhausted Sam is and how despirate he is for sleep. I also believe that he is as manipulative of "his kids" as he intends to be to Richard.
As far as the kids are concerned, they should suck it up and move on. The slave behaved how anyone of them would have, trying to make contact with the real world. Why would they expect any less of Richard. They seem to me to be like abolishionists who didn't really want anything to do with the actual real life black slaves. If they don't accept their own role in the problem I will think a great deal less of them. I will certainly think less of them if they are actually cruel to Richard. You may cage a lion, but you don't beat it, when you're in the same cage.
Sam seems to want Richard to be completely broken, makes me wonder why he didn't buy a female convert (generally would be more broken and more passive) mayb e females don't live in that environoment for long.
Stockholm syndrome could certainly be a factor for Richard, however, Sam will have to take the time to develop a 'relationship' with Richard for that to take effect. Also the syndrome can work both ways and a part of me wants to see Sams reaction if in a year or two the canary gets its head burnt off.
I am glad that you are showing Richard as being more then a mouse, most intelligent people will bend and not break until conditions are truly inhumane and for an extended period of time. An intelligent Richard might choose to be insane, that also would be interesting.
There my very long comment. Reduced down just says love the story, please keep writing and I'm impressed at the speed.