He would need to do his first mission first, which is to go to the Tomb of Gemini and retrieve the Sword of Gemini. Everything else after that we can make up as we go.
The young knight is not really with an order, he just a young knight in a whole legion of knight who are mercenaries, hired by the King in times of need or the real knights who guard his castle. Your pick could be one of the two. The only thing that separates you and the other knights is that you were blessed by a Wandering Prophet, and you have been given a destiny at such a young age (compared to others, who must discover it by themselves).
Would you want this to be a Solo game, where you are the young knight at after the skirmish at the Tomb, you are the only one left, or would you like a companion?