The largest percentage of the Akhetan population, slaves are in such a great supply that they tend to be owned by everyone who is a successful Ritta or higher in the caste system. Their owners are allowed to treat them however they wish, and abuse is considered a personal quirk rather than anything frowned upon. The Draconic Council even uses slaves as magical experiments.
The reason for the large number of slaves is due to the fact that Illumians are stingy regarding freedom. Any Non-Illumians, or those descended from Non-Illumians, are automatically slaves. Disgraced Illumians often become slaves as well. The slave population is so large that most major Illumian cities were entirely built by their labor.
There are some free non-Illumians, but it is a rarity, and is only in existence because of the arena.