] I found it really interesting that the first time Catherine speaks to Henry, she actually has the guts to disagree verbally with him (about a lady's supposed ability to write charmingly)!

In this conversation, JA shows not only why Catherine is disposed to like Henry, but also why Henry might like Catherine.

She's the perfect audience for a clever and witty young man inclined to indulge himself a little too much with the foibles of others.

She has enough of a sense of humour to appreciate his wit, and tries not to laugh when he steps over the line; she understands what he's doing when he leads Mrs Allen on. It's the right balance between joining in on the one hand, and being prim and disapproving on the other.

In addition, she's a perfect feed: time after time she gives him an opportunity to be witty. But she's not stupid and insipid: she does stand up to him (as in that passage).