There are ambiguities around Fanny's character and the influences which shape her that I find troubling. What follows is in note form because I am having difficulty articulating what is bothering me. I'm not trying to draw up a complete picture of Fanny here - just focusing on aspects which seem relevant to this troubling ambiguity.

Influences:

Childhoood poverty, maternal indifference. Sent away from her family at age ten.

Institutional oppression: Fanny is "Not a Miss Bertram". Treating people very differently because of differences in social rank was normal in Georgian society but is shown to be unjust in the novel. It appears very wrong today in the light of ideas about equality and human rights etc.

Georgian conventional view of ideal female behaviour (eg Gregory's "A Father's Legacy") - JA satirised aspects of what conduct manuals recommended, but IIRC was quite pleased with aspects of Gregory. Appears unreasonable, disempowering and unjust from a modern perspective

Religion: Teachings include "Love one another", "Blessed are the meek", "Honour thy father and thy mother" (Sir T and Lady B are 'in loco parentis').

Mrs Norris persistent persecution (amounting to child abuse). Fanny cannot love her.

Sir Thomas: Well intentioned but emotionally distant, cold, formal. As paterfamilias he is all-powerful. Fanny is afraid of him.

Only Edmund and William give Fanny any encouragement or consider her needs and feelings.

Characteristics:

Physical weakness - possibly related to childhood poverty.

Timid and fearful and shy - How much is innate and how much the result of oppressive influences?

Hyper-emotional - extremes of feeling.

Hyper-sensitive (1.) to accusations of selfishness and ingratitude. Fanny tries so hard to be good and to think 'as she ought', but when the accusations are unjust why doesn't she ever protest, at least inwardly? (Vocal protest would do little good as she is powerless and dependent.)

Hypersensitive (2.) to things which she finds distasteful; eg she feels "pained" by her father's coarse language and smell of spirits (38). Wouldn't distaste or disgust be more natural? Perhaps this is just using the word 'pain' in it's broadest sense.

Hypersensitive (3.) to things which contradict her strict and upright morality. Mary Crawford is often the offender. Fanny does not love Mary. Her judgements are morally correct, but she is racked by jealousy of Mary because of Edmund - does this encourage Fanny to find Mary's faults?

Humility, meekness: Big ambiguity here. Religious teaching promotes these qualities (Beatitudes - see BarbaraB's post and ensuing thread). At the same time it seems to me that Fanny's humility stems at least in part from the fact that she has been systematically crushed and her sense of self-worth undermined by Mrs Norris' persecutions and the indifference of most other characters to her needs and feelings. This does not seem healthy to me.

Gratitude: Various influences tell Fanny that she ought to be grateful; JA tells us that she has "strong feelings of gratitude" (48). Fanny is unaccustomed to receiving encouragement, positive kindness or affection, so we see how pathetically (as it appears to me) grateful for any crumbs which come her way. For this reason Fanny's gratitude seems an ambiguous quality - the mark of a 'good girl', or the result of emotional starvation??