Who is Atum-hadu from The Egyptologist and what is their importance?

Atum-hadu is the Egyptian king who captures Ralph Trilipush's obsessive interest. The king may not have ever existed, but Ralph believes that a papyrus scroll he calls Fragment C suggests that the king did exist. Ralph translates and interprets Atum-hadu's poetry, from which he invents a life story for the king. According to Ralph, Atum-hadu is born to poverty, becomes a great general, then attains the throne of Egypt. The king's sexual appetite knows no limits, and he has no sympathy for his enemies. He loses his kingdom to an invading army.