Book - Bartimaeus Trilogy

A series of three books (thus the word trilogy), created by Jonathan Stroud. The universe of this serie is a world where wizards rule. The main story is based in England, where all the important post including the Prime Minister are all wizards. All these wizards will take up a apprentice to train them to also work for the govt. and another thing, all these wizards can summon djinnis or demons and make it do their bidding.

So the three main characters are:

1. Bartimaeus - A mid level djinni that has a fascinating history. A djinni that has many names and is written frequently about in history books. Became the main djinni for Mandrake, a wizard.
   
2. Nathaniel or John Mandrake - An apprentice in the first book and became a full-fledge minister in the second. Summon Bartimaeus as his first djinni. Naive at first but gradually became a bit arrogant and big-headed.
3. Kitty Jones - A commoner and rebel. Rebelled against how the wizards treat commoners as lower beings.
   

This is the first book that I can remember that uses a djinni as a main character. We can see the growth of the main characters develop nicely. Some famous people that you might heard off also make a cameo in this trilogy. Its a good read and a book that I would recommend.