I agree that Isabella has an agenda. It is too easy to dismiss her as a boy-crazy flirt. Instead, as a previous poster noted, Isabella is beginning to think matrimonially. She is not staring down spinsterhood yet, but the next few years are critical. Since Mrs. Thorpe is "a widow, and not a very rich one," there is reason to believe that Isabella may be concerned about her prospects. Just think of how agitated Mr. Henry Dashwood (chapter 1) and Mr. Bennet (chapter 8) were about their daughters' situations and prospects. Isabella is no better, and may very well be worse off financially. To add to the pressure, if she doesn't marry, she will have to rely on John Thorpe to support her! But, being Isabella, she is not going to marry the first man to come along. No, she is looking to secure a husband that will do her credit and keep her in style. James Morland is the leading prospect, but she is keeping her eyes open, just in case that doesn't pan out or something better comes along. In short, Isabella is the object of Isabella's affection.