The story I'm looking for I read in the first half of the 2000's, I'm fairly certain the title had the word "Vesuvius" in it, but I'm not absolutely sure. It was a short novel, not more than an inch thick. Language is English.
The story was set in Pompeii just before the famous eruption; the main character was a young (Greek possibly?) slave who was a skilled artist. The main plot revolved around him escaping the city with a wealthy man's daughter, her secret soldier lover, and a smuggler. A major subplot involved him creating a painting or fresco of the wealthy man's daughter, and he chose to draw her as Andromeda, with the soldier as Perseus, the smuggler as Medusa's head, and her suitor as the monster Cetus.
I remember it being unusual in that it was a story about Pompeii where the characters survive the eruption.