The subject of courtesans has come up more than once on the list;
recently, I was directed to a series of books in connection with a
peripherally-related topic. I found the books in question to be
well-written, with excellent world-building, and the protagonist an
excellent example of a courtesan.

I thus commend to your attention the three books composing the first
third of Jacqueline Carey's _Kushiel's Legacy_, sometimes referred to
as the "Phèdre Trilogy", consisting of the novels _Kushiel's Dart_,
_Kushiel's Chosen_, and _Kushiel's Avatar_. Be advised that it treats
certain mature subject matter quite frankly, but I cannot say
gratuitously.