Onirarch
An oneiriarch, or "dreamlord", is a member of the elite caste of the oneiriarchies who benefit from the dream energy gathered from the masses of the citizens. The term is somewhat ambiguous: sometimes it refers to only the actual leaders of the nations, at other times it refers to those who work magic fueled by the stolen dream energy (who may or may not be the political leaders), while at other times it is used to refer to any of those who, with the leaders' sanction, knowingly benefit from the dream drain, which may include categories as diverse as local leaders, friends and family of the leaders and spellcasters, and on rare occasion even people who discovered the oneiriarchs' plans and were allowed to share in their lifestyle to keep them silent. (It is not, however, generally used to refer to agents and employees of these people—the servants and spies that the oneiriarchs have working for them—even though they do also benefit indirectly from the stolen dream energy and also know of the oneiriarchs' plans.)
Compared to the common people whose dreams they despoil, the oneiriarchs (whichever definition one uses) generally live lives of luxury. Sometimes the oneiriarchs live in completely different ways than their victims, as notably in Risinien, when the oneiriarchs and their servants are the only inhabitants of the nation to retain human form. At the other extreme is Xolia, where the oneiriarchs and the other citizens share the same hedonistic lifestyle, largely indistinguishably... except that the oneiriarchs are not killed on reaching adulthood to harvest their ghosts as undead dream engines. Most oneiriarchies fall somewhere in between; the dreamlords are a privileged class, living apart in rich dwellings, attended by servants, and enjoying comforts and exotica unavailable to the common man (except perhaps on the black market. They do occasionally pass among the people, but they live on a different level.
Becoming an Oneiriarch
The first oneiriarchs became oneiriarchs by being the first oneiriarchs—that is, by founding an oneiriarchy, by skimming off the dream energy of an area's people and using that to gain power and get themselves declared leaders. It's still possible for new oneiriarchies to be formed that way today; there is still some area not claimed by developed nations, and it's possible in principle for someone in that nation to follow the path forged by the dreamlords of the past. In fact, this has actually happened recently, in the formation of the "savage oneiriarchy" of Rronga.
In an existing oneiriarchy, however, the most common way that one becomes an oneiriarch is by being related to the existing oneiriarchs. The oneiriarchs form something of a closed community, and generally court and marry among themselves—it has sometimes happened that an oneiriarch falls in love with a "commoner" and introduces him or her into the ranks of the oneiriarchs, but this isn't at all common. It also sometimes occurs that an oneiriarch can befriend a commoner and decide to bring him into the elite, but this, too, is rare—the oneiriarchs just don't typically mix with the hoi polloi enough to form such relationships with them. Still, this is more likely in some oneiriarchies than others—it's far more probable in a nation like Ivinii or Drithidiach or the aforementioned Xolia where the oneiriarch actually do interact with the people more than in one like Plakhán or Risinien where the oneiriarchs live completely apart.
There are other ways of becoming an oneiriarch, but they are, if anything, even less frequent. Sometimes an oneiriarch might decide to elevate a particularly favored servant into the life of the privileged. As mentioned above, it has also happened that some individuals who somehow learned of the oneiriarchs' nature were inducted into their ranks themselves to buy their cooperation, but this isn't normal—more often such people are likely to be quietly disposed of or turned into zombies, unless an oneiriarch is for some reason particularly fond of them.
Law Among the Oneiriarchs
In general, the laws of the common people do not apply to the oneiriarchs—even if the dreamlords may pretend they do in order to give the commoners an illusion of safety and control and keep them docile. Though there are exceptions, in most oneiriarchies a dreamlord who decided to torture or otherwise mistreat a common person would not be disciplined or even chided for it. As far as most oneiriarchs are concerned, the commoners exist only for their power and amusement.
Though they can ignore the commoners' laws, however, that doesn't mean the oneiriarchs are above any laws. Other oneiriarchs may not care if commoners are hurt or inconvenienced—but they do if they themselves are. Depending on the nation, there may or may not be explicit laws governing punishments for oneiriarchs who damage other oneiriarchs; sometimes the ranks of the oneiriarchs may be too few for such rigor to be necessary. It's certain, though, that an oneiriarch who goes against the interests of his superiors will be punished, and that includes going against the interests of the oneiriarchs as a group—an oneiriarch who tries to champion the common man against his fellow dreamlords is unlikely to last very long.