Looking for a specific series.

Hi I read a series a few years back set in a fictional Roman/Hellenistic universe were Pompey had never erupted, it seemed to be almost set in a world where Ars Magica (the TTRPG) was the world setting (they kept talking about The Order of Hermes) and one of the characters was a young student with an affinity for fire. Anybody got any clue as to what it was called?