Okay, so every group of vampires normally has their leader. In Obsidian there is a whole system of vampires.
At the top of the hierarchy, you have the Emperor, followed by his chosen family. You don’t see the Vampire Emperor in Obsidian, but he becomes a main character in the next books.
The council is next on the list. The council advises the Emperor and watch over the districts. These are the men you see at Psytech just before and after they buy the Herrick-Peyton building in Hilo.
Down the line are the vampires who are employed by Psytech. These vampires are given more power since they are especially loyal to the Emperor.
After Psytech employees are all other vampires. This includes vampires who are simply loners and some who are rebels. Rebel vampires, like Perry Eberly in Obsidian, are frowned upon, but the Emperor believes they are still better than drudges and humans.
Drudges are humans who want to be vampires and seek out ways to become one. Once they pass many tests and prove their loyalty they may become Vampire Guardians. These are special vampires who are charged with protecting important vampires.
Lowest on the “food” chain are the humans. According to most vampires, once the vampire race rules, they won’t have any rights.
And that is that. Here’s a little chart to give you a visual look at the Hierarchy.