"Shadow Duet" is a short story with the same setting and characters as her 18th century historic fantasy novel Masks and Shadows, featuring the famous castrato singer Carlo Morelli and his accompanist-lover Baroness Charlotte von Steinbeck. (Needless to say, their relationship--which was established after the end of the novel--is something of a scandal.) I'd call this work more of a character sketch than a short story, to tell the truth. Our characters are in London where Morelli is performing and the story is entirely encompassed by a society party where Charlotte encounters all manner of reactions to her existence and relationships from the upper class attendees and meets a number of real-world artists who have a somewhat broader-minded reaction. But there is no plot, as such, simply a great deal of delightful description and conversation.
I wouldn't recommend this work to anyone who hasn't already read Masks and Shadows, but if you have and you're thirsty for just a bit more of the characters, "Shadow Duet" should do the trick.