I don't know; Susan did have trouble "keeping the faith," to continue the metaphor. Remember in Prince Caspian? No one but Lucy could see Aslan at first, but Susan had the hardest time with it. Totally adored Edmund there. "Let's follow Lucy--I'm sure she's right." And I thought that in Voyage Susan got to go to America, because she was the beauty and needed opportunities. I thought I remembered that she was becoming a bit stuck-up. I haven't read the Chronicles in a long time, though.