Cast Away, Now He Is a God

The divine court has an illegitimate son it never claimed. Caius grows up with the word bastard attached to his name, raised by his mother alone, outside every hall that mattered. His mother falls under a curse that will kill her, and the price for lifting it is his service to Zeus, so he goes up to the realm of the gods and takes the place he was offered. What he learns after arriving is that he was never brought in to serve anyone. He is material for the Titan Seal, a life to be spent holding it shut, and the gods discussed it among themselves as an obvious use for something like him. He decides he will get his mother out and that the whole divine realm will pay for how it has treated both of them.