After they'd plated everything up, Marian looked up at him. "Thank you," she said, and there was a genuine pathetic gratefulness there. Yes, he was a monster and he was destroying them, but at least he was letting them have this. She knew this would mean so much to the boys, starving and cold and suffering.
Marian figured that if she showed herself to be grateful, if she played the role he wanted from her, then this might happen with more regularity. They'd be rescued soon enough, but until then Marian could use her own kindness and willingness to believe in the best - a thing so often her downfall with these bastards - to their advantage.