How does Bertha Rochester help in the development of the plot in Jane Eyre?
Well, think about it. Without Bertha, we would not have the rest of Jane's story. Bertha is the catalyst for Jane to leave and go with St. John. She is the reason why Jane and Mr. Rochester cannot be together. She is the reason for his moodiness; she drives the conflict in the novel, even before Jane knows about her. The story of Jane and Mr. Rochester would be short and fairly sweet without the fact that he had a crazy wife hidden in his house. Because of Bertha, Jane loses her innocence, an important quality for a female at that time. Her eyes are opened to the real world and she realizes that things are not only not what they seem, but that she does not have control over her destiny as a woman. She later gains insight and comes to terms with her own destiny, but without Bertha Rochester, she might never have grown as a person in her own right.
The moment we are introduced to thge Thornfield Hall we develop an air of mystery due to the mysterious room in the third floor with all hideous happenings and also we encounter certain happenings in the novel like a candle left out Jane's room the burning of Rochester's bed and the tearing of the wedding veil so all these develop an air of suspicion. Finally when Bertha is introduced to us the mysteris an suspicions are unraveled further through the technique of flashback the skeleton in Rochester's cupboar is explained so we can come to the conclusion that the employement of Bertha contibutes to the plot in two ways namely
1-The plot of mystery and suspicion
2-The plot of Bertha's background and Rochesters involvement with her