One aspect I found striking after reading Jane Eyre was the short life expectancy amongst the adults. This was different to Dickens' Great Expectations, in which many of the major characters survive into their sixties, eventually dying of unnatural causes. At the start of that book, all of Pip's family except his sister are dead, and Pip's sister later dies due partly to Orlick's assault on her. However, if you survived into adulthood, the chances of your reaching old age appeared quite good. In Jane Eyre that does not seem so true. There seems to have been only one character who survived into old age: Mrs Fairfax. Jane's parents and her uncle on her mother's side die while Jane is a small child. Jane's aunt, the mother or St John, Diana and Mary Rivers, has died some while before the main events of the story. St John, Diana and Mary Rivers' father has died shortly before Jane arrived at their home. Jane's other uncle, John, also dies during the course of the book. In addition, Jane's aunt Reid and her cousin George die about half way through the book. Lastly, St John Rivers is reported to be dying, presumably while in his thirties, in the last chapter of the book. This is in addition to Helen Burns and the other girls who died at Lowood School. Unlike Great Expectations, none of these people died violent deaths. They all died from illness, although George's early death was brought on by his dissolute life style, while St John's death was hastened by his missionary work in India. The only character who suffered a violent death was Bertha Rochester, who jumped off the roof of Thornfield Hall (iirc).
Maybe this partly explains why Jane is happy to marry a man twenty years older than her. She knows her constitution is weak, while Rochester's is strong. Maybe she was not counting on lasting a long time. Jane has a dread of emigrating to India where she thinks she would quickly die. Diana Rivers tells her it is a place which kills the strong while Jane is weak and wouldn't last three months. This is another aspect I was slightly surprised about. Pip spent some time considering whether to take a commision in the army, presumably with the The East India. He didn't in the end, but did emigrate to Eygpt with Herbert and his wife, where they all seemed to thrive. Angel Clare from Tess OTOH, emigrates to Brazil for a while, catches Yellow Fever and is very ill. Angel's friend in Brazil also catches fever and sadly dies.