It was AU, and steampunk-ish. I loved Gabriel (the inventor), he was quiet and somewhat shy, but participated in political protests to abolish or at least change the caste system which was very unfair. Lucio was the companion (escort). He was born into this caste and like Gabriel he had a tattoo on his hand to show this. Anyway, they meet and like each other because Gabriel treats him like a person and not a sexual object (gasp!). This is the story of how they get together (in this society that was quite the adventure.)
There are scenes where Lucio has sex with women and sex with other men. This made sense as he was a companion and couldn't just quit. It's not until someone buys a companion's contract can they quit working and become monogamous. There was also a plot line that I thought was left dangling and that made the rating go down. Overall, it was a good read.