I am going to introduce two terms here to differentiate the Brontë sisters, composers and translators. A composer is one who imagines things and then writes down the inspiration. A translator looks at real life and puts it into the novel.
It is curious that M. Heger stormed at Charlotte. He could not understand why her compositions were so much better than her translations. I think she had an original soul. She felt constrained by already-present texts, and could not grasp the entirety of their meaning. Now when expressing herself she was vivid. She was a better describer than analyst - she is not so clear-cut as Emily, as she once wrote to William Smith Williams, that Emily's true strength was as an essayist.
It is strange, that despite Emily's superior arguing skills, when it came to novel-writing, it was Emily who composed and Charlotte who "translated." By which I mean, Emily conjured characters out of her own imagination e.g. Heathcliff, an unbelievably demonic being, who despite being not very realistic, transcends time and emotion i.e. revulsion. This is what critics thought made it a genius, despite the disgust they felt on reading it. Emily cared less for present externals then her two other sisters, and so this reflects in her characters. Even the incidents, adopting an orphan (though it's based on a true story) is more legendary than realistic. It is the stuff that feeds stories. She was the best poet among the sisters, and her Gondal saga seems to have been the sort of thing with epic heroes, dungeons and high feelings - not the thing literary fiction appreciates, more's the pity. If you are talented and passionate it is not very hard to make up some passionate heroes and heroines with exciting adventures. Without wars and events her characters would have languished away, I suspect. This reclusive woman lived on events. Yet very few of us are gifted with that power, simple though it seems in theory. We are more realists. When it came to her essays Emily wrote what she thought, argued it through, clearly and cuttingly. When she wrote of a historical figure, she made him into a brave hero, the sort to be admired in a poem from afar. You see him in a distant land, towering above the rocks or something. This is the stuff of poetry.
Charlotte on the other hand was a "Translator." She analysed real people and transcribed them into the text.. Unlike Emily, she had to know the person in order to create a vivid character out of them. Which is why the characters in Shirley are so convincing - they are based on real people. The 3 curates Malone, Donne and Sweeting were actual people she had met in real life. And after the book was published they took to calling each other by their fictional names. More than transcribe them from real life, she had to analyse them, and see how they would react in different surroundings. Her best characters are not simply made up or type-casted. Caroline is sweet but weak, Mr Helstone good but stern and unfeeling, Mr Yorke a cultured Radical with family pride - these are real people. Dr John is kind-hearted but ultimately shallow. In her Brussels essays she liked to describe feelings from within. Her historical figure is shown to be insignificant-looking, but a brave man. She looks at him from inside - sees him as flawed, unheroic, personal. Less effective than Emily, but still has its charm. Ironically her early Angrian tales are full of passion and malevolence (reminiscent of Emily) but this gave way as she grew older to bleak reality. Her Villette characters are marvellous - seen in a biased manner of course, but we are here to see Lucy Snowe's perception of characters rather than merely the actual characters as they really are.
Anne on the surface is a translator - because all her characters are believable. She refuses to glamourise a bad boy like Rochester or Heathcliff, going in for the kill. Agnes Grey is drawn from life, which makes it a transcription (rather than Charlotte's more sophisticated "Translation.") Tenant of Wildfell Hall is an achievement, because it analyses characters and pronounces judgement on them. I do not like the over-moralistic tone but otherwise it is a good story. Arthur Huntingdon is partly based on Branwell, but certainly not fully based, as Branwell was more intellectual and sensitive, and Huntingdon is a rich, sophisticated gentleman, which Branwell certainly wasn't. Huntingdon is drawn from a type rather than Branwell. There is a possibility that he was based on an abusive husband Anne heard of, whose wife came to the Parsonage. (Check Juliet Barker's The Brontës for the details) which makes the portrait more realistic, but it is still based on a type of abusive husband. Gilbert Markham too is a type - the gentle, good-natured man who will not listen to gossip. The gossipers in the village especially the nasty strict Rev. Millward are obviously types, but better-drawn than your average novel.
So what is Anne? A translator or a composer? To make a character from a type needs some originality, which makes it a composition. On the other hand so many features of that type are already present for the writer to use, and all it takes for an excellent writer is to bring it to life, give it more realistic detail - and bravo! you've got a character. Anne must be in the middle. Which is unusual, as we are used to seeing Charlotte in the middle (at least 19th century critics thought so). Anne was not the only novelist to employ typecasting - Dickens was susceptible to it, Thackeray to some extent (George Osborne and William Dobbin are types, no matter how well-drawn they are) and even her sister Charlotte (though those characters are not her most vivid). It's more early Victorian than late Victorian, which is perhaps why the novels of the early Victorian era were more entertaining and enduring (I know there's Sherlock Holmes, Dracula and H Rider Haggard, and I love Rider Haggard, but those are not literary fiction, and the fact the late Victorian classics are more adventure shows you something about how literary fiction changed to boredom.) There's an essay about how realism became so photographic it became dull and meaningless. But anyway Anne does not stoop to that level. I will call her a transcriber, something Charlotte does since she copies from life, but Anne copies from type, which makes it slightly different. Even the reality of Agnes Grey is not without the impression you are seeing the bad sides of most people, which make them types rather than fully-fledged people, but she was 25 at the time. Mr Weston too is a type though he might be fairly convincing. Agnes herself is the best-drawn but compared to Helen Huntingdon she seems more type-ish, but that could be due to her youth. Youths can be less complex, more frank and ardent.