Sex god vs Mortal role play

A sex god captures a rapist and makes it mandatory that he serve him as a concubine. After much begging and pleading the sex god relents that if he learns all the sorcery that he can and defeats the sex god, he will give him his freedom back, but must be the god's concubine until then. In the meantime, Jake, the name of the character must serve the sex god submissively and learn his spells and magic in the meantime.