'I [Arthur] know that all your devotion centres in this room, and that nothing to the last will ever tempt you [Amy] away from the duties you discharge here. If I were not sure of it, I should, before now, have implored you, and implored your father, to let me make some provision for you in a more suitable place. But you may have an interest--I will not say, now, though even that might be--may have, at another time, an interest in some one else; an interest not incompatible with your affection here.' [...]
'No. No. No.' She shook her head, after each slow repetition of the word, with an air of quiet desolation that he remembered long afterwards. The time came when he remembered it well, long afterwards, within those prison walls; within that very room.
'But, if it ever should be, tell me so, my dear child. Entrust the truth to me, point out the object of such an interest to me, and I will try with all the zeal, and honour, and friendship and respect that I feel for you, good Little Dorrit of my heart, to do you a lasting service.'
'O thank you, thank you! But, O no, O no, O no!' She said this, looking at him with her work-worn hands folded together, and in the same resigned accents as before. (1.32.52-60)
And all that dutifulness comes back to bite Amy in the rear end. Sure, Arthur is as usual totally clueless about what she's really feeling and instead just wants to be her friend/surrogate dad. But here, she is totally hosed by the fact that everything Arthur is saying about her being her dad's slave is actually true.