The second volume of Jane Austen’s Northanger Abbey really revealed how Isabella serves as a foil for Catherine. Isabella has an obsession with male attention and physical beauty that highlights a stark contrast between the two companions.
When Catherine receives the letter from her old friend, she realizes she is appalled at the girl’s complete lack of faithfulness and penchant for deceit. Catherine proclaims that she is “ashamed of Isabella, and ashamed of ever having loved her” (190). I saw Isabella’s gold-digging personality as an exaggerated metaphor for the expected behavior of women at the time. It was widely perceived that the key to a woman’s success was in marrying well, and Isabella’s exaggerated prescription to the feminine roll to entrap a rich husband is Austen’s way of spurning such a silly ideal. By having Catherine renounce the other girl as a friend, Austen is metaphorically renouncing society’s unrealistic expectations of women. By having Isabella end up unsuccessful in her pursuit of a rich husband, Austin opposes the false claims of popular romantic ideals.
Isabella, as Catherine’s foil, furthers Austen’s development of Catherine as an unlikely heroine and atypical girl overall.