Warning: Wikipedia contains spoilers!
He is born the heir of House Atreides, a nuclear-armed aristocratic family that rules the planet of Caladan.
In Dune, he loses his family, but is embraced by the indigenous Fremen as their messiah. In accepting the mantle of godhood, Paul launches the Atreides on a course that spans 10,000 years through the next five books.
In Dune Messiah, he has been emperor for eight years. His jihad has killed sixty billion people across the known universe, but according to his prescient visions, this a fate far better than what he has seen. Paul is beleaguered by the need he sees to set humanity on a course that doesn't lead to its stagnation and destruction, while at the same time managing both an empire and a church built around him.
At the end of Dune Messiah, Paul walks into the desert, a blind man, leaving the children in the care of the Fremen while their aunt Alia rules the universe as regent.
His son Leto is the central character of the remaining books.