Pride of Purchase
Adam Pierce is unusual -- not for his money, which is hardly unexpected in a man who can afford to engage a Companion for a week's time -- but for his youth. He is two years younger than Inara, and while she's had young clients before, they are usually supported by family, whereas Pierce, according to his dossier, is alone in the 'verse.
When they meet for the first time, she is startled again, this time by the wealth of experience in his green-hazel eyes. She'd half-expected a green boy, despite the sophistication his application video had shown, and when it turns out that sophistication was merely the tip of the iceberg, she can't help feeling a bit overwhelmed. His education is as extensive as any Companion's, and their conversation ranges over such topics as the literature of Earth-That-Was, the political situation facing the border planets, and the history of the tea ceremony.
They talk for hours before he finally kisses her, and when he does, she realizes with a start that he's seducing her -- and that he's doing an excellent job of it.
Author's Notes: Written for a 'first kiss' prompt from catithadage.