Well, Jason was the next in line for the throne but his uncle took it. When Jason came on age he was the going to take his throne but his uncle said that he would give him his throne back if Jason could prove he was a hero by finding the Golden Fleece. His uncle thought it was an impossible thing to do, and he thought  that Jason would fail and never be king. But when Jason came back with the Golden Fleece, and Jason became king.

What Jason did!!!