Marcher Lord

Marcher Lords are powerful figures who are allied to various city states. They control territory on the outside and act as the first line of defense. Their jobs include defeating bandits, managing what resources there are and ensure that the rule of law of the city-State is kept. They can be hereditary, but some city-states force the next in line to go through rigorous training and tests before being allowed to inherit his father's seat.

While the first born (originally it was primogeniture, but about the beginning of the Era of the Pillars, it changed to first born, whatever gender) is the usual inheritor, they do not have to, especially if there is a more competent member of the family. Those who do not inherit may find work as administrators of the land, or go to work in the City-State.

Example: Verlin Kimaris was the fourth son of a poor Marcher Lord outside of southern Paroskov. His father could not support him, but was able to send him to be trained under Rosh Quervet. Due to circumstance, he rarely spent time in the southern keep, instead living in the city itself. His eldest sister actually took over after his father died.

This is fairly typical. Much of the time younger children who do not care to stay at home find some work, military or otherwise.