Who is Eumenes from Time's Eye and what is their importance?

The Royal Secretary to Alexander the Great, Eumenes is older than most of the King's close companions, and served King Phillip as well as his son King Alexander. From Cardia, Eumenes' career advances with King Alexander's. He is efficient, intelligent and knows the value of political subtlety which earns him the King's undying confidence. He is ambitious, and builds a large fleet to sail down the Indus intending to open a new trade route.