Isilel
Does military service raise one's nahn/dahn?
Let's say somebody from a very low nahn, who is basically a serf, right? I mean, they don't have the freedom of movement. So, what if a man like that rises to a sergeant and serves 25 years with distinction, does he go back to being a serf when/if he retires from the military? Would he be required to return to his village/town of origin? Can something like this be properly controlled, even? I mean, do they check traveling people's papers?
Brandon Sanderson
There's a lot of parts to this. Rising within nahns and dahns happens more easily in Roshar than rising in social status did in most societies that had similar things in our world—for instance India, or even England. To an extent, it is very easy to buy yourself up a rank. What you've got to remember is the very high ranks are harder to attain. By nature, the children of someone of a very high rank sometimes are shuffled down to a lower rank—until they hit a stable rank. There are certain ranks that are stable in that the children born to parents of that rank always have that rank at as well. Your example of the soldier who serves with distinction could very easily be granted a rank up. In fact, it would be very rare for a soldier to not get a level of promotion if they were a very low rank—to not be ranked up immediately. The social structure pushes people toward these stable ranks. For the serf level, if you're able to escape your life of serfdom and go to a city, often getting a job and that sort of thing does require some measure of paperwork listing where you're from and the like. But if you were a serf who was educated, that would be pretty easy to fake. What's keeping most people as serfs is the fact that breaking out of it is hard, and there are much fewer of those ranks than you might assume. The right of travel is kind of an assumed thing. To be lower ranked than that, something has to have gone wrong for your ancestors and that sort of thing. There are many fewer people of that rank than there are of the slightly higher ranks that have the right of travel. It's a natural check and balance against the nobility built into the system. There are a lot of things going on here. Movement between ranks is not as hard as you might expect.
Isilel
Ditto with the lighteyes—does exemplary service raise one's dahn?
Brandon Sanderson
It's much harder for a lighteyes, but the king and the highprinces can raise someone's dahn if they want to. But it is much harder. In the lower dahns, you can buy yourself up in rank. Or you can be appointed. For instance, if you're appointed as a citylord, that is going to convey a certain dahn, and you could jump two or three dahns just by getting that appointment. Now, if you serve poorly, if a lot of the people who have the right of travel leave—which this doesn't happen very often—if your town gets smaller and you're left with this struggling city, you would be demoted a dahn, most likely. If a lot of the citizens got up and left, that would be a sign. They could take away your set status by leaving. That’s something that’s built into the right of travel. So these things happen.
Isilel
If parents have different nahns/dahn's, how is child’s position calculated? For instance, if Shallan had married 10-dahner Kabsal, what dahn would their children belong to?
Brandon Sanderson
The highest dahn determines the dahn of the child, though that may not match the dahn of the highest parent. For instance, there are certain dahns that aren't conveyed to anyone except for your direct heir. The other children are a rank below. I believe that third dahn is one of the stable ranks. If you're the king, you're first dahn. Your kid inherits. If you have another kid who doesn't marry a highprince, and is not a highprince, then they're going to be third dahn, not second, because that's the stable rank that they would slip down to, along with highlords and the children of highprinces.
Isilel
Or, and another thing—what happens if a lighteyed child is born to darkeyes or even slaves? Which should happen often enough, given that male nobles seem rather promiscuous. Anyway, are such people automatically of tenth dahn?
Brandon Sanderson
The situation is very much taken into account in these sorts of cases. Normally—if there is such a thing as normal with this—one question that's going to come up is are they heterochromatic. Because you can end up with one eye of each color, both eyes light, or both eyes dark. That's going to influence it a lot, what happens here. Do you have any heirs? Was your child born lighteyed? This sort of thing is treated the same way that a lot of societies treated illegitimate children. The question of, do I need this person as an heir? Are they born darkeyed? Can I shuffle them off somewhere? Set them up, declare them to be this certain rank. Are you high enough rank to do that? Are you tenth dahn yourself? What happens with all of these things? There's no single answer to that. The most common thing that's probably going to happen is that they are born heterochromatic. Then you're in this weird place where you're probably declared to be tenth dahn, but you may have way more power and authority than that if one parent is of a very high dahn, just as a bastard child in a royal line would be treated in our world.