The Legion of Videssos (Videssos Cycle, Book 3)

Since the Roman legion had been mysteriously transported to this world of magic, tribune Marcus Scaurus had served the rulers of war-torn Videssos well. He had been largely responsible for ousting the Pretender and putting Thorish Gavras on the throne. That, of course, made him a hero.
Rome or Videssos, however, Fortune was a fickle goddess.
Now he and the legion were returning in triumph to Videssos the city after defeating a well-entrenched army of rebel mercenaries. But Marcus, betrayed by the one closest to him, was returning to be seized, dragged before the Emperor, and questioned under truth-drug like a traitor.
Of the court, only Alypia Gavra stuck by him -- but consorting with the Emperor's niece was dangerous. It could lead to exile -- or death!
Yet Alypia was attractive. And Marcus was lonely . . .