the laughter according to the introduction by R. Brimley Johnson in one of the editions. The wrath because of the follies and insincerities of fashionable romance, with its absurd heroics and artificial emotions.

In another edition Richard Church writes in the introduction;

"It is obvious that this early savagery must have had a cause. It was not personal, for Jane's family life was harmonious. Her parents and brothers and sisters (sic) adored her and fostered her talents. [..]The cause was aesthetic. Jane's creative nature was rebelling against contemporary literary fashion in the novel, its absurd inflation of human sensibility, its preoccupation with niceties of the marriage market, its snobbery and pettiness."

So this wrathful rebelling could have resulted in this ruthless way of writing.