You are Horus, son of Osiris.

Osiris is giving his speech, declaring the next king to rule all of Egypt. He finally announces Horus(You) his son, and the Lord of Air, to be the king of all Egypt. Seth is late to the declaration, but still brings a gift for Horus.

-Ah, my nephew, Horus, never fails to impress me, here I bought a gift for you!

Seth pulls out a old Horn, worth over 1,000,000. Horus(You) blow into the horn, and a huge army comes up on the stage in front of all the people of Egypt.

-Well, looks like someone caught your attention.

Seth stabs Osiris in the chest as Seth was trying to fight Osiris, and Osiris dies, and now you have to take his revenge.