# How can I keep the number of demigods limited, but stable?

In this world, there is a group of demigods that functions as a religious organization. This organization operates worldwide and defends the realm from threats of a demonic parallel realm. There are also places where the realms bleed into each other, allowing those demonic energies to corrupt certain areas and mutate the creatures there. This has led to the creation of various races that are hostile to humanity. Therefore, this group od demigods are necessary for humanity's survival.

This group functions out of monasteries, with one on every continent. They replenish their numbers by recruiting from that continent's population. There are about 1000 demigods in each monastery, give or take depending on the time period. Children around the age of puberty are tested for the "divine spark", a sign that they have been chosen by the gods to serve a higher purpose. This is a significant moment for a clan, and they are honored by society due to their contribution to protecting the realm. The children are then infused with the divine essence through a powerful ritual performed by their inductors that converts humans into gods. Those found compatible will be inducted with a 100% success rate, and raised at the monastery to become warriors. These children will lose their memories of former lives in order to devote themselves fully to the realms protection. The process also turns them sterile, to remove the ambitions of forming lineages. These demigods live between 1000 and 1200 years.

I want to make these special children a rarity in the world to make it a big deal when one is found, but I also want to keep the numbers of demigods stable around the figure I gave previously. This world is similar to ours, with approximately 7 billion people living on it. How can I make this work?

• Do they all die at age 1000, or do they have a death rate? – L.Dutch Nov 15 '18 at 13:00
• Attrition rates? How many die per year "defending the realm from threats of a demonic parallel realm"? – nzaman Nov 15 '18 at 15:00
• "There are about 10,000 demigods in each monastery." That's a decent sized town, not a monastery!!! (That's not a criticism of the concept...) – RonJohn Nov 15 '18 at 15:16
• "10,000 demigods in each..." I'd say, this world is demigodly – Alexander Nov 15 '18 at 18:12
• What kind of a big deal should the birth of a child with a spark be? Should it be a big deal to the family or clan? The continent? The world? The figures you give come to about ten births a year, which means that each live birth is likely to hit CNN when it happens, but not as a major story. – David Thornley Nov 15 '18 at 19:03

Let's say your initial world population is P.

If each year the likelihood of a suitable baby to be born is $$\alpha$$, the number of suitable newborns is $$B= \alpha \cdot P$$.

Out of the demigods, each year a fraction $$\beta$$ dies, so at year $$n$$, indicating with $$n-1$$ the year before, your population of demigods D is given by

$$D_n = D_{n-1}\cdot (1-\beta)+ B = D_{n-1}\cdot (1-\beta) + \alpha \cdot P$$

If you want to keep a stable population of demigods, the number of suitable child born each year has to cover the losses.

• If the average demigod is getting 1.000 years old. Then only 10.000/1.000 = 10 people die per year in average, meaning around the same number of birth are happening, if the Population is constant. When the average lifespan is only 600 years due to fighting you have less than 20 deaths per year. – user55267 Nov 15 '18 at 14:42

The "divine spark" is not biological. It is not appearing randomly in population. It is truly divine.

There is a limited number of these sparks in this world, and as the old demigods die, new ones are getting the spark. If children with this spark get the divine essence, they will develop into demigods and live a long time. If not, they would remain dormant and die in a relatively short "mere mortal" time.

There can be a shorter number of demigods in this world if their ranks are getting depleted and young children are not getting the essence, but there won't be a demigod overpopulation, because only so many divine sparks can exist.

There needs to be wriggle room. Don't make it all about the genes, because then you end up with whatever numbers pass that test. Require more subjective testing as well, like for intelligence and personality.

If the number of children who qualify is larger than the number you normally need to cover attrition in any given year, you can use the other requirements to choose the number you need. Some of the rejected children might be chosen in the following year. If you keep the process mostly hidden, no one will know who is rejected or why.

You also don't say what age these children are? Aren't the parents objecting to you killing their children? You're not killing them, you say. You're elevating them. Yeah, but if you erase all their memories, then the body is just a shell and the brain just potential. The parents will never have contact with them again. It's effectively murder. (If these were newborns then you wouldn't bother to say their memories were erased, and it would still be as if they died to the parents.)

• This reminds me of The Tombs of Atuan. – RonJohn Nov 15 '18 at 18:04
• I admit I have not read any of the Earthsea series. But thanks, I've added it to my Goodread's to-read list. – Cyn Nov 15 '18 at 18:10

The spark is transferable upon death. When a demigod dies, the spark goes to a baby born at the moment of the death.

Should the baby die before manifesting, it moves again to a new host.

With this method you have a set number of sparks and just new hosts when the old host dies.

As with any magic system, there should be a limited hard rule making even the most powerful being limited by a clear vulnerability/mechanics. i.e. Warbreaker feautures demigods who need a normal citizen to sacrifice their magic to them, one person per day, or the demigod dies, so the number of demigods that can be sustained is technically limited directly by birth rates.