Bertha and Jane only meet face-to-face twice, and they never have any conversations, but, as Rochester’s two wives and as the two higher-class-than-the-servants residents of Thornfield, they’re still odd doubles of one another. Both are in many ways outsiders or "Others," both have passionate sexual desires for Rochester, and both seem a little bit eerie or supernatural. Of course, Jane’s a sometimes-mild-mannered plain-faced English girl of eighteen, and Bertha’s a crazy Creole woman twice Jane’s age, but what’s really weird is that these major differences start to pale in comparison to their similarities. And that makes us ask: could Jane ever share Bertha’s fate? She seems to think it’s possible when she tells Rochester that she knows he’ll get tired of her after a year.
Though St. John and Rochester never meet, we’re definitely contrasting their different relationships to Jane in our heads all through Book III of the novel. Jane rejects Rochester’s illicit passion and his attempt to commit bigamy and/or make her his mistress, but she’s even more appalled by St. John’s desire to make her his legal wife and sexual partner without love or passion. St. John may be more correct in the eyes of the law and the Lord, but the demands he makes of Jane are much more disgusting than Rochester’s. Remember, Jane goes back to Rochester not because she knows he’s single now but because she’s got to get away from St. John.