[The prince] began to examine the portrait in his hand. He longed to solve the mystery of something in the face Nastasya Philipovna, something which had struck him as he looked at the portrait for the first time; the impression had not left him. It was partly the fact of her marvelous beauty that struck him, and partly something else. There was a suggestion of immense pride and disdain in the face almost of hatred, and at the same time something confiding and very full of simplicity. The contrast aroused a deep sympathy in his heart as he looked at the lovely face. The blinding loveliness of it was almost intolerable, this pale thin face with its flaming eyes; it was a strange beauty. (1.7.46-47)
"Oh, aren't you ashamed of yourself—aren't you ashamed? Are you really the sort of woman you are trying to represent yourself to be? Is it possible?" The prince was now addressing Nastasya, in a tone of reproach, which evidently came from his very heart.
Nastasya Philipovna […] walked quickly up to Nina Alexandrovna, seized her hand and lifted it to her lips. "He guessed quite right. I am not that sort of woman," she whispered hurriedly, flushing red all over. Then she turned again and left the room so quickly that no one could imagine what she had come back for. All they saw was that she said something to Nina Alexandrovna in a hurried whisper, and seemed to kiss her hand. Varya, however, both saw and heard all, and watched Nastasya out of the room with an expression of wonder. (1.10.61-64)
[Nastasya] was in full dress this evening; and her appearance was certainly calculated to impress all beholders. She took [Myshkin's] hand and led him towards her other guests. But just before they reached the drawing-room door, the prince stopped her, and hurriedly and in great agitation whispered to her:
"You are altogether perfection; even your pallor and thinness are perfect; one could not wish you otherwise. I did so wish to come and see you. I—forgive me, please—"
"Don't apologize," said Nastasya, laughing; "you spoil the whole originality of the thing." (1.13.39-42)