Aetherians and Xelusians - same species, very different kingdoms (ee-thir-ēə zel-oo-sēə)

Aetherians and Xelusians have many qualities that make them special, but the three most significant come from their physiology and are;
1. Greatly reduced aging due to an altered mitochondrial clock. During childhood ten human years equals one Aetherian year, for example a child who is 35 years old chronologically is a toddler. Karstien and Damien were in their 80s when their mother Lady Aimee was lost at sea, that made them physically, and emotionally equal to an 8 year old human, even though mentally they are more intelligent, they still have the behavior of that age group. Pure Aetherians can live up to ten thousand years, but more, however the more human heritage the less effective this trait. For example, Adamos, who was pure Aetherian, lived to almost 10,000, and Lord Orion was closer to 14,000. However Karstien's son, Arturo who was slightly more than half human, only lived 1300.
2. Greatly accelerated healing factor. In Climate of Change and Ancient Ice Age, Daisy wishes she had Aetherian physiology (spoiler alert- be careful what you wish for). Aetherians can heal at the same rate as someone using a standard healing potion. However, the more human heritage, the slower the healing.
3. Redundant physiology. Aetherians have a backup system in their bodies; a minor second heart, nerve nodes that store energy to jump start their system and brain when they revive, and blood that holds many times the oxygen of human blood. When an Aetherian sustains enough damage, they will die forever but usually they fall into a deep comatose-like state that mimics true death. Their body rapidly heals (even faster than their normal accelerated rate), then the redundant systems "revive" the "dead" Aetherian, usually close to full health but not always. Human Heritage of half or more erases this trait, the result being that half-Aetherians die and do not revive just as a full human would, although their ability to heal faster means they survive wounds that would kill a normal human. But even half-Aetherians have double the life-glow ( a measurement of life energy) when at full health than a human. They are also stronger and longer lived than humans.
Some Aetherians have the ability to call on types of magic beyond using books, potions, and enchantments. For example: Warrior Magic, allows for Speed, Strength, Night Vision, Dual wielding, and Resistance to Damage. Huntsman's Magic increases Sight for targeting or threat assessment (like a zoom lens), Power, Swiftness, Climbing, and Stealth (like invisibility). While most Magic is channeled through potions, books, and objects, the Royal houses of the Aetherians have the ability to tap into the magic of their blood and bloodline or their station.
~~~~~~~~ For Example: As the crown regents, both Karstien and Princess Allura have the ability to use an enchanted object called the Flame of Aetheria. It works as an amplifier of magic and protection element. Some can use magic from their inborn gifts and through the power of their will without spellbooks, potions, or enchanted objects. For Example: A Guardian has the strongest warrior magic, making them nearly invincible. For Example : the War Oracle is the only oracle who uses the Light of the Oracles as a weapon and defense. ~~~~~~~
Aetherian Healers have the ability to heal others ( although they can not mend bones), 'shine' and enemy to make it friendly or at least less hostile, and to read minds/souls (although it is considered a violation of their healer vows to do so against someone's will. The healer Lady Asha, has the ability to make someone sleep, regardless of their training and to generate a healing light or mist that can affect both the body and the mind. Aetherian Oracles use their magic to have visions and heal souls. Xelusian Oracles became something else and use their magic to control and manipulate people. Mages of both kingdoms can use magic but Xelusian Mages also use blood magic, the consuming of another's blood/life-glow and through it gain access to the blood-givers magic, strength, healing, or other innate/inborn magic. Blood magic often becomes an addiction and is particular dangerous for those with warrior magic, leading to insanity and death. Many of the Royals use both enchanted items and their inborn magic.

Basic Information

Anatomy

Humanoids, mammals, non-human aliens - would be classes Homo Aetherius
Males are often over 6'6" tall or 2 stones(meters)
Females are often 5'8" or taller.

Genetics and Reproduction

Quad helix DNA
Children reproduced similar to humans but with a 21 month gestation. Twin births are more common than single births once every few centuries. The influx of human DNA increased the rate of fertility to every decade, but decreased the life spans of those carrying human DNA.

Growth Rate & Stages

Pure Aetherian infants age at a rate of slightly less than one decade per human infant year equivalent. They reach their teen years between around 160 but are not considered young adult until 200, maturity is reached at 400 when they seem to stop aging completely and only show aging per millennium or because of the use of dark magic.
The more human DNA an aetherian carries the faster they age. Half-Aetherians have a life span of 1,000 years but as an infant they grow at 3/4 the rate of a normal human child.