One racial stereotype is that slaves were happy.
Slaves were often afraid to express disagreement to their masters or in front of their masters. The fear of reprisal may or may not have been recognized by the slave owners. However, it was pretty easy to pretend that they were happy. An example is the suggestion that Dick should have the slaves interviewed by a Boston newspaper “so that they may see how contented and happy our darkeys really are.”
Dick Owens wants to marry Charity, but she thinks he is worthless. She will not marry him until he has done something.
"I'll run off one of the old man's; we’ve got too many anyway. It may not be quite as difficult as the other man found it, but it will be just as unlawful, and will demonstrate what I am capable of."
So when Dick finds his father’s servant, Tom, he asks him if he wants to take a trip up North.
"I would n't min' it, Mars Dick, ez long ez you 'd take keer er me an' fetch me home all right."
Dick knows that Tom is lying, but of course Tom is just reinforcing the idea that he is a gentle and happy and is not going to contradict any white man. He just goes along with it. Dick does not really care. He is only interested in proving his worth to his girl by doing something, and he is not at all interested in helping to free a slave.