The distant future is not what most would expect. Instead of an advanced civilization, most of the planet is covered in a medieval society. An eon of wars and natural disasters have wiped out the civilization as it is today, annihilating all buildings, roads, and man-made structures. All the weapons have been used in battles until they nearly fell apart; the natural upheavals quickly destroyed what was left. Hundreds of wars have scattered the technology and only fragments of useful information have survived. These fragments have been used to create things like levi-ships, plumbing, and agriculture. Weapons, communication, and travel technologies remain in their most primal forms. The worst change, or possibly the best depending on perspective, is the mutations that have arisen due to chemical and nuclear warfare. Though mother nature has finally been able to balance the environment so these pollutants are no longer wreaking havoc, the effects of these contaminants have permanently altered many species, including humans. From the mistakes of the past has arisen many new races, including demons, winged humans with a sharp, scorpion-like tail, werewolves and other werebeasts, humans prone to changing fully or partially into an animal form and swayed by the changes of the moon, sorcerers, humans able to weild and control the very fabrics of reality itself, and many other creatures once only thought of in mystical stories and fanciful fairytales.
The most powerful of these creatures is undoubtedly the demon because of its ability to fly, but any of these creatures could have overthrown the humans if it weren't for several genetic flaws that arise in the other species. While all of the creatures were stronger than the humans, had an equal or higher intelegence, and had a longer lifespan, they also had much lower birthrates and a tendency toward homosexuality that kept their populations low enough for the human race to be at least a threat, often times a match.
The power struggle between humans and demons currently rests in the demon's favor. That did not mean, however, that humans were enslaved or mistreated. Years of shifting balances between the two races and several enslavements of both races by the other had taught them not to mistreat each other, less they be mistreated in turn. The demons have control of the government, which simply means that most the demons in that area, which is usually in the area of ten or twenty, hold a position in the government and the head of the government falls under demon rule. Of course, loner demons that prefer to work alone are fairly common since some demons find it hard to remain in one place for a long period of time. These demons often become bounty hunters, guards, thieves, or leaders of rebel groups. Many times they will settle if they find a mate, not necessarily of the opposite gender, but some remain freelance all their lives, which is generally two to three hundred years.
This extended lifespan is also shared by most of the creature developed by ancient wars. Sorcerers, werebeasts, and many others share this lifespan with demons, though there are a few that have lifetimes shorter than that of a human.
One would think, with such a low birthrate, that even with the longer life the demons would face extinction due to the low birthrates. And on many occasions this has been true, the demons almost died out many times simply for a lack of new blood. It is only human greed that saves them. When the demon population grows to low the humans overthrow them, often making them the most prized bed slaves of the household. Because the demons are so popular they are often forced to mate with human females, and the resulting child is always a pure demon, since demon genes are able to dominate all other genes thus ruling out any possibility of a half-blood.
This world, seemingly dangerous and chaotic, is in actuality not all that different from the world to day; there are still monsters waiting for careless action, still people to fight those monsters, still wars fought by politics between politics, still people trying to make things better and people trying to make things worse. The story is the same, only the characters are different.