I came up with this character concept while playing the strategy game Total War: Rome II. If you download the new “Desert Kingdoms” DLC and play as the kingdom of Kush, you start the game with a scout character named Ozalces as part of your retinue. Since the character’s name and his avatar’s physical appearance both appeared Greek rather than Kushite to me, I figured he would be a Greek immigrant from Ptolemaic-controlled Egypt.
In my personal imagination, the character Ozalces abandoned his loyalties to the Ptolemies after coming to sympathize with the oppressed native Egyptian population, and so fled to Kush in search of powerful allies who could help him liberate Egypt from Greco-Macedonian rule. Since then, he has served as a scout and spy on behalf of the Kushites. I think a storyline like that would that would make a fun movie or historical fiction someday.