In Kids 2 Kings, we learn of the complicated relationship between Ausar and his Grandfather Rah. Well, all things have origins and this situation is no different. Sons of Nibiru goes into Rah's past, before he was Pharaoh. It shows the complicated relationship he had with his creator/father Nun.
These books are linked and are of the same universe. It is a great time to get both at a fraction of the cost.