In Wide Sargasso Sea, "Bertha Mason" is portrayed as being a false name for Antoinette Cosway. The character of Jane Eyre and Antoinette are portrayed as being similar, independent, vivacious, imaginative, young women with troubled childhoods, educated in religious establishments and looked own by the upper classes. also they both marry Rochester. however Antoinette is more rebellious than Jane and less mentally stable.
Antoinette is the protagonist in the novel. when the novel begins Antoinette is a lonely young girl growing up in post-emancipation Jamaica. after an escalating series of of violent encounter Antoinette and her family of white creoles are forced to flee from their estate. after that she was forced to a marriage with Rochester. rest of the tale describes her complicated and uncomprehending life with her husband. delusional and paranoid Antoinette awakes from a dream and set out to burn down the house.
The book purports to tell Antoinette's side of the story as well as Rochester's and detail how she ended up alone and raving in the attic. According to the book, Antoinette's insanity, infidelity, and drunkenness are the result of Rochester's misguided belief that madness is in her blood and that she was part of the scheme to have him married blindly.
Antoinette is a far cry from the conventional female heroins of 19th and 20th century novel, who are often more rational and self restraint.