Two thumbs way up for The Course of Honor by Lindsey Davis. Historical fiction.
A fictionalized version of the love between the Emperor Vespasian and his mistress, the freedwoman Caenis. When I first started reading The Course of Honor, my reaction was a bit WTF? And I won't lie, the writing style is unique to the point of peculiarity. At a certain point, however, I fell in love, peculiarities and all. I have only one way to convey how much I adore this book: A month after I finished it, I picked it up again and re-read it. Cover to cover. Because now that I knew how much I loved it, I wanted to enjoy all of it, without the hesitation of the WTFiness I had originally experienced at the beginning. Caenis, oh prickly brave unsentimental Caenis, is you have dethroned Jane Eyre - yes, Jane Eyre - from my post of favorite romance heroine. And Vespasian, unlike almost all romantic leads, is worth falling in love with. Now, great characters falling in love and hooking up is all well and good; what makes this book worth re-reading - and the reason that I have labeled it "historical fiction" rather than "romance" - is how heartbreaking it is. To me, a romance cannot be truly great without a contrasting sense of mortality and loss to put the love into sharper relief. That's what this book does. It's not about love, really - well, it is - but beyond that, it's about the bravery necessary to balance love and duty. I won't recommend it unreservedly, because it's peculiar and unique and not for everyone. But me, I would want it on a desert island.
In the hall the steward Aglaus was hovering. Caenis spoke to him calmly. "Aglaus, I shall be going out this afternoon." She laid her hand for a moment on Vespasian's togaed arm as he followed her. "This gentleman is someone I have known for a long time. If ever he comes here he is to be received as a friend of the house. Mind you" - she lifted her hand again - "he's the type who turns up for one or two meals, kicks the cat, spanks the kitchen maids, then disappears again for twenty years."