Re: Percy Jackson and the Olympians
the premise is that the Greek mythos is alive and well in the current world. As Western civilization has moved west, so has the gods. Currently, Mount Olympus is above the Empire State Building.
The main characters are all half-blood children of the gods. Percy Jackson is the son of Posiedon, the only currently surviving decendent of one of the big three (Zeus, Posiedon, Hades). The big three made a pact after WW II not to breed with humans, as those children tend to cause a great deal of mischief. That pact has been broken twice since then,