Historic novel with folklore elements "The sultan, the vampyr and the soothsayer"

The timeperiod is just before the conquests of Constantinople by the Ottomans. The main characters telling the story are Sultan Murat, heir Mehmet, a consort, a visir, Vlad Dracula, his father and some religious men.

The multiple person account makes it hard to identify with one character. And with all Greece philosophy, folk superstition and such it is a difficult read. What remains is the thought what a nasty madman Mehmet the Conqueror was. But when you look in a real history book that is all the more clear: he liked young boys. Not only the brother of Vlad the Impaler but also the son of a Byzantine Duke who he ordered to give him the child and when the father refused he murdered/ enslaved the whole family and carted the boy off to his bed anyways. However in those days young girls were treated similarly. Different times indeed.

AMAZON blurb:
" 1442: When Vlad Dracula arrives at the court of the Ottoman Sultan Murad II, his life is turned upside down. His father Dracul cannot protect him; he must battle his demons alone. And when the Sultan calls for the services of a soothsayer, even the shrewd teller of fortunes is unprepared for what he learns.

Meanwhile, the Ottoman Turks are advancing through the Balkans with Vienna in their sights and Constantinople, the Orthodox Greek capital, within their grasp. As Eastern Europe struggles against the tide of a Muslim advance it cannot counter, Western Christendom needs only one prize to overthrow its enemies."