• Demons are partially immortal. They do not die of old age and it's highly unlikely that they'll become ill. However, they can be killed, and often are, keeping the population in check.
• How is the demon lord population so low? Well, while commons and warriors would have a difficult time taking down a fully grown lord, infants are considerably weaker. In addition to the low lord birth rate, commons and warriors will often team up to kill the young, thereby earning themselves more freedom from the lord's reign. Some do make it to adulthood, but it is not with the help of their parents. The only demon who will protect her offspring is the queen.
• One of the only edible substances
in the demon realm is, in fact,
other demons. Demons require some sort of sustenance; though they can get it from a variety of means, killing and consuming other demons is a favorite. However, demons are reputed to taste
horrible and have a stringy texture. This may be one reason why they are so eager to form faerie alliances and eat their foods.
• For the record, though they do eat, demons do not require a toilet or similar location. They do not "use the bathroom".
• For those demons that bear a resemblance to a particular animal, it is best
not to refer to said demon as "(animal) demon". To be compared to a "lesser" creature is an insult in demon society.