A Song Of Ice And Fire: The Golden Stag

A son born between Cersei Lannister and Robert Baratheon, with bright blue eyes and black hair like a Baratheon. He was spirited away from his birth place and birth right by his uncle Jaime Lannister.
But, unknown to Cersei and Jaime, the child understood everything that they have planned together. With that as his driving force, the boy grew powerful than his ancestors and parents, and came back to his birth place, only to see it's in the turmoil of war.