When we read Jane Eyre in my Victorian Lit course in university, the professor mentioned Wide Sargasso Sea as an interesting further exploration of Bertha Mason and her relationship with Rochester. 
 For some reason - perhaps because I'd associated it with Jane Eyre - I assumed that Wide Sargasso Sea would be a large tome, something that would require a substantial investment of time, so I put off reading it for years. But when it came up in my search for books to read for my Reading Around the World project, I decided it was time to just bite the bullet and get 'er done. 
 It's a very interesting story, covering Bertha Mason (or, rather, Antoinette Cosway)'s childhood as the child of white former slave owners - rejected by the English as "Other" and half savage, yet rejected, too, by her black neighbours. She is hated by all as her mother, after a series of tragedies and mistreatments, loses her mind. 
 The story continues in Rochester's voice after their marriage, as he struggles to understand this mysterious woman who is so different from the English women he is familiar with. Recovering from a fever, confused, frightened in an unfamiliar environment and with unfamiliar people, he turns against his new wife. 
 It's an interesting story, and a very interesting companion to Jane Eyre. It's a short read and interesting, though rather feverish in its stream of consciousness (it does, after all, show a descent into madness), but I found that the added perspective greatly enhanced my relationship with Charlotte Bronte's work.