Isabella’s actually a pretty minor character in Emma, which is interesting, because Austen goes to a lot of trouble to describe her as the perfect woman. She’s a doting mother, a devoted wife, a loving daughter, and a perfect hostess. She also happens to have inherited her father’s fear of diseases (and love of doctors), but that’s a minor blemish on an otherwise pristine character. As Mr. John Knightley’s wife, Isabella spends lots of time at home – mostly because Mr. John Knightley likes spending time with his family as much as Isabella does.
So why does Isabella get so little screen time? Well, perhaps that’s because perfect women just aren’t all that interesting. If things are always going well, there’s not that much to talk about. After all, who wants to hear about dentists? Or babies? Or…gruel? (If you’re that someone, you might want to find yourself another novel. And maybe some new hobbies.)
Isabella does serve as a pretty great foil to Emma, though. She may be the perfect wife/mother/woman, but she’s just not as exciting as Emma can be. Mr. Knightley’s always comparing Emma to Isabella, and it’s pretty clear that Emma gets the better of her sister in his mind. We’re not surprised.