Miss Thorpe and Miss Tilney are not only opposite in their looks and behaviour. It struck me that Catherine´s first encounter with both of them is very different also.

With Isabella she seems to have no problems to reach a rather intimate level, ch.4: Their conversation turned upon those subjects, of which the free discussion has generally much to do in perfecting a sudden intimacy between two young ladies: such as dress, balls, flirtations, and quizzes. But obviously that "intimacy" seems to be quite superficial...

Her first encounter with Miss Tilney on the other hand doesn´t seem to go further than exchanging pleasantries - ch.8:But the hindrance thrown in the way of a very speedy intimacy, by the frequent want of one or more of these requisites, prevented their doing more than going through the first rudiments of an acquaintance, by informing themselves how well the other liked Bath, how much she admired its buildings and surrounding country, whether she drew, or played, or sang, and whether she was fond of riding on horseback.

At first this seemed odd to me. But then I realized that the second encounter was more natural. If you meet somebody for the first time you´ll probably not step too deep into conversation as you don´t know the other person yet. So the quick intimacy with Isabella should have made us suspicious rather...