the firelight like an ill-looking enchantress

I had no longer any doubt on the subject. With a lightened heart, though with a profound sense of the weighty importance of my task, I devoted the whole afternoon to the composition of the draft of this letter; for which great purpose, Agnes relinquished her desk to me. But first I went downstairs to see Mr. Wickfield and Uriah Heep.
I found Uriah in possession of a new, plaster-smelling office, built out in the garden; looking extraordinarily mean, in the midst of a quantity of books and papers. He received me in his usual fawning way, and pretended not to have heard of my arrival from Mr. Micawber; a pretence I took the liberty of disbelieving. He accompanied me into Mr. Wickfield's room, which was the shadow of its former self - having been divested of a variety of conveniences, for the accommodation of the new partner - and stood before the fire, warming his back, and shaving his chin with his bony hand, while Mr. Wickfield and I exchanged greetings. To cut the matter short, I said I would have the other room or none at all; so it was settled that I should have the other room; and, taking my leave of the firm until dinner, I went upstairs again.
I had hoped to have no other companion than Agnes. But Mrs. Heep had asked permission to bring herself and her knitting near the fire, in that room; on pretence of its having an aspect more favourable for her rheumatics, as the wind then was, than the drawing-room or dining-parlour. Though I could almost have consigned her to the mercies of the wind on the topmost pinnacle of the Cathedral, without remorse, I made a virtue of necessity, and gave her a friendly salutation. She never left off, or left us for a moment. I had arrived early in the day, and we had still three or four hours before dinner; but she sat there, plying her knitting-needles as monotonously as an hour-glass might have poured out its sands. She sat on one side of the fire; I sat at the desk in front of it; a little beyond me, on the other side, sat Agnes. Whensoever, slowly pondering over my letter, I lifted up my eyes, and meeting the thoughtful face of Agnes, saw it clear, and beam encouragement upon me, with its own angelic expression, I was conscious presently of the evil eye passing me, and going on to her, and coming back to me again, and dropping furtively upon the knitting. What the knitting was, I don't know, not being learned in that art; but it looked like a net; and as she worked away with those Chinese chopsticks of knitting-needles, she showed in the firelight like an ill-looking enchantress, baulked as yet by the radiant goodness opposite, but getting ready for a cast of her net by and by.
At dinner she maintained her watch, with the same unwinking eyes. After dinner, her son took his turn; and when Mr. Wickfield, himself, and I were left alone together, leered at me, and writhed until I could hardly bear it. In the drawing-room, there was the mother knitting and watching again. All the time that Agnes sang and played, the mother sat at the piano. Once she asked for a particular ballad, which she said her Ury (who was yawning in a great chair) doted on; and at intervals she looked round at him, and reported to Agnes that he was in raptures with the music. But she hardly ever spoke - I question if she ever did - without making some mention of him. It was evident to me that this was the duty assigned to her.