u/BOtgod2O

I remember reading a book somewhere around 2015-ish where the characters lived in a massive city that was broken up into different castes. The highest level was purple, and the one character who was purple was the queen of the city or something? At one point the main character sneaks up to the purple level and meets the queen.

The secondary main character is a girl who works in the lowest level in boiler rooms. She is a slave, I think? at some point she sneaks up to the level where the main character lives, and he hides her.

The lowest caste are slaves, and there is one scene where the main character witnesses a slave being prepared to be sent up to serve one of his relatives and they cut out the slave's tongue, I think?

Thanks for the help!