Still mulling the notion that the fantasy novels of Tolkein (read only once or twice) and C.S. Lewis (re-read yearly) have their sources in undisclosed wartime travels in the Balkans and elsewhere. Lunatic notion, but the second Lewis novel has clear resonances with his American travels, and the others seem to have a similar verisimilitude -- and the overarching theme is an Englishman type coming into contact with distant cultures. And then there's the powerful City contacts of Charles Williams. (My hierarchy puts him between the two.)
Every work of fiction is an invitation to fictionalize the life of the author.