Why I rarely read historical fiction

Marguerite Yourcenar has been on (and off) my to-be-read list for many years; after seeing the movie Coup-de-grace based on one of her novels I've tried to find that novel in my local library - no luck. then Fran Liebowitz opines that MY's 1951 novel, Memoirs of Hadrian, is a truly great novel - I would not have expected Yourcenar to be at the top of Liebowitz's reading list - so that's what I'm reading now. Generally, I'm not drawn to historical fiction, such as the Hilary Mantel Cromwell trilogy: reading historical (especially historical-biographical) fiction I sometimes thinks, well, why am I not reading a biography? What value is the novelist adding to this material? The answer is that the novelist has the freedom to share (i.e., invent, surmise) the subject's thoughts, feelings, secrets. Can the novelist invent incidents? Probably, but with caution (remember that ridiculous "authorized" Regan biography that invented heroics to demo the late president's character?!). Like most contemporary readers outside of Classics departments, I know almost nothing about Hadrian so Yourcenar has a free pass there. The 1st section of the novel is pretty strong; we see Hadrian at 60 on his deathbed and thinking about his life as he begins a (book-length) letter to his successor in waiting, Marcus Aurelius. Well we know Marcus was not only a Roman emperor (the last one, if I can recall correctly) but also a great writer - people still read his Meditations (some people, anyway). Hadrian, at least in Yourcenar's imagining, is similarly literary; the opening section is full of some really thoughtful insights into the pleasures and pains one endures in the course of a life. In fact, the pages in which he (Youncenar) ponders the nature of sleep (and its relation to both health and death) are worth the price of the book alone. That said, as the novel moves into the 2nd section and Hadrian begins recounting his early life and political rise, particularly through his military career, the purpose of the novel begins to blur: MY doesn't develop incidents in deapth (this is not the Confessions of Saint Augustine), there are just a lot of name-checks, although there are some intriguing insights into Roman military strategies. I also like that Hadrian rose to power in the Roman Senate as an excellent writer, who penned speeches for the emperor (Dacius?) and others - the first communications officer! Reading forward, still pondering: Hy Hadrian? What's so important about him? And how does this add value beyond a well-written, fact-based biography?