How and when it all began she could not clearly remember. Her aunt had another guest, a Swede. He talked of his work, his people, the latest Swedish novel. Somehow, she herself did not know how that terrible fascination of glances and smiles began, the meaning of which cannot be put into words.
These smiles and glances seemed to reveal to each, not only the soul of the other, but some vital and universal mystery. Every word they spoke was invested by these smiles with a profound and wonderful significance. Music, too, when they were listening together, or when they sang duets, became full of the same deep meaning. So, also, the words in the books they read aloud. Sometimes they would argue, but the moment their eyes met, or a smile flashed between them, the discussion remained far behind. They soared beyond it to some higher plane consecrated to themselves.
How it had come about, how and when the devil, who had seized hold of them both, first appeared behind these smiles and glances, she could not say. But, when terror first seized her, the invisible threads that bound them were already so interwoven that she had no power to tear herself free. She could only count on him and on his honour. She hoped that he would not make use of his power; yet all the while she vaguely desired it.
Leo Tolstoy: The Forged Coupon and Other Stories