...of mutuality

He made Armande’s acquaintance in a Swiss railway carriage one dazzling afternoon between Thur and Versex on the eve of his meeting with Mr. R. He had boarded a slow train by mistake; she had chosen one that would stop at the small station from which a bus line went up to Witt, where her mother owned a chalet. Armande and Hugh had simultaneously settled in two window seats facing each other on the lake side of the coach. An American family occupied the corresponding four-seat side across the aisle. Hugh unfolded the Journal de Genève.
Oh, she was pretty and would have been exquisitely so had her lips been fuller. She had dark eyes, fair hair, a honey-hued skin. Two dimples of the crescentic type came down her tanned cheeks on the sides of her mournful mouth. She wore a black suit over a frilly blouse. A book lay in her lap under her black gloved hands. He thought her recognised that flame-and-soot paperback. The mechanism of their first acquaintance was ideally banal.
They exchanged a glance of urbane disapproval as the three American kids began pulling sweaters and pants out of a suitcase in savage search for something stupidly left behind (a heap of comics - by now taken care of, with the used towels, by a brisk hotel maid). One of the two adults, catching Armande’s cold eye, responded with a look of good-natured helplessness. The conductor came for the tickets.

[Transparent Things, Nabokov, V.]