Well the goal of the High King having children is so a good heir can step forward. The legitimate children are trained to rule, and those who are not elected High King are usually given governor positions after their parents' death. Royal bastards are more like the wildcards in the Game. They can come from any background (their birth would have been recorded). Lowborn bastards wouldn't have been raised in court. but bastards of noble women could have been raised alongside the others, but with more freedom. 

You could write more than one character or add your own NPCs, I'll do the same. Magic and races wise, we'll treat it as a traditional high fantasy game, so Elves and Dwarves, although Matal is a human Kingdom. Magic is prevalent and a skill to be learned just like swordsmanship. 

Matal itself can be compared to old France, with a powerful upper class, established priesthood and poverty stricken lower class.