@kylie_aliah @ghostkun The old man presumably thinks that what he's doing is less evil than what the lady does. He enslaves the body, but (he believes) the lady enslaves the soul instead. The lady will overwrite the boy's personality and he'll become her, losing his identity and humanity. And while death (and perhaps, afterlife) is an escape from slavery, there's no escape from the lady. Also, it may be that the boy would be an indentured servant rather than a slave, which means he could eventually be free (though that's not much consolation if he dies).
I'm not saying I agree with this argument, but I think it highlights the difference in two points of view. The old man probably has enough money that he doesn't worry about starving or having to do dangerous work to feed himself, so he thinks the boy should value his identity over having a comfortable life. The boy, on the other hand, has always been mistreated by the world, always been hungry, and never been loved, so he values love and comfort over his sense of self. There could also be a religious component- the old man doesn't see suffering in life as a big deal if you get to go to heaven afterwards, whereas the boy has actually suffered throughout his life and is focused more on this life rather than the next one.