It took all of Narcissa's will not to curse him. He voluntarily left her son behind? That was even worse than leaving him because he had to in her opinion. "While the task was completed don't you believe that the students need someone strong and sure of themselves to lead them through these troubled times?" she asked him vaguely. Yes she did mention all students but she was just talking about her son.
Narcissa glanced at him curiously like there was something she didn't quiet understand. "Last I heard he was doing fine. He hasn't been telling us much," she admitted softly.