Diana Wynne Jones said this quote

After that, all the while Millie was eating the pudding... we both tore Christopher's character to shreds. It was wonderful fun.... He drove everyone mad in Chrestomanci Castle by insisting on silk shirts and exactly the right kind of pajamas. 'And he could get them right anyway by magic,' Millie told me, 'if he wasn't too lazy to learn how.... But the thing that really annoys me is the way he never bothers to learn a person's name. If a person isn't important to him, he always forgets their name.'When Millie said this, I realized that Christopher had never once forgotten my name...