Lucy In 'Prince Caspian'.

“Lucy has such an open mind,” says Georgie Henley, who plays Lucy in Prince Caspian.  “She is very trusting.  I think that Aslan sees that in her.  He shows himself to her first because he knows that she will believe he is actually there.  She won’t think it is just a vision or fleeting thing.  He is not just a wild lion.  She didn’t let her siblings beat her down about her beliefs which is why I think Aslan believes in her a bit more.”
http://www1.cbn.com/movies/prince-caspian-faith-through-a-childs-eyes