Now, I haven’t finished the book, in fact I have only read maybe 30 pages so far, but Ilium by Dan Simmons could be a fit. It features a character that is tasked by a divine entity to explore the events of Homers Iliad. It is Sci-fi though and I am not sure if the book will keep this characters storyline in Greece or even under this pact.
If someone has actually read the whole book (series) please chime in!