Kelpies in the All World Mythos
Anyone who knows anything about Celtic mythology knows about the kelpie, a water demon appearing as a black or white horse (and sometimes as a gorgeous woman) that lures unwary victims to their bogs, drowns, and eat them. The trick is for the kelpie to get its victims on its back, upon which the victim cannot get off again. Some stories say that getting on a kelpie breaks the illusion it has on itself. Once it snares its prey, it leaps into its bog or loch and proceeds to feed on its prey.
My favorite way to describe this particular demon’s true form is the possibly cliched undead zombie horse, to fit in with its rather horrifying legends from around Scotland and Ireland. My kelpies are a bit more expansive in nature and I gave them a backstory while I was coming up with an excuse not to kill off Muramasa, a kirin of chaotically evil power. In the series proper, the Kelpie Race is all but extinct with just one specimen still surviving, the kelpie Thanatos. The kelpies’ origins and methods of reproducing disqualify them from Nation status (their eradication nulls it anyway). Eliminating them beforehand also suits my personal rule that nothing undead belongs in All World (which includes vampires and zombies).
The kelpies were a small race but the first kelpies were made in the same way and they had then spread their taint across the world before the Purge, the mass-extinction event that eradicated them from the face of the earth. A band of living horses were corrupted with chaotic evil (the same evil that resides in the kirin Muramasa). They were subsequently killed and the chaotic evil inside them brought them back as the first kelpies. The horses gained human-level sentience and sapience. They were driven by a fierce hunger but they were clever and picked up a few tricks in illusion by secretly observing the Fox Nation. They are also driven by intense lust, which figures in how they exploded into a recognized race and threat.
After the first band of horses, the Kelpie Race usually added to their numbers through deception and rape of other equines. The initial corruption of chaotic evil has never appeared since in a living being, until the birth of Muramasa. They rarely went after humans for anything other than prey, even though they were capable of casting an illusion on themselves that made them appear human. Kelpies are incapable of breeding with their own, given their undead status. Instead, a kelpie stallion will seduce a living mare and subsequently rape her to ensure she carries his spawn. Kelpie mares are completely barren so it’s all on the stallions to add to their numbers.
As physical contact of any kind breaks the illusion, the kelpie will often dedicate much of their power in upholding the illusion while simultaneously keeping the mare placated and receptive. Once he’s done with her, he promptly breaks the illusion, revealing what he is to the mare as a way of boasting his conquest of her. Often the mare becomes psychotic with grief, shame, and the fact she was seduced by a kelpie. However, the lingering effects of the kelpie’s power prevents a mare from taking her own life, allowing the spawn to grow inside her and have a meal upon birth. The spawn usually reaches full maturity at an unnatural pace, resulting in birth in less than a month. Sometimes, the mothers got away. Sometimes, they didn’t. It depends on how strong the mother is from giving birth.
When the kelpies were still numerous, they were successful in creating other kelpies from three of the four Equine Nations plus horses. The only Nation they never managed to touch in any form was the Kirin Nation. The first kelpies came into existence roughly after kirins vanished from the mainland, having relocated to Island Reptilia. That could change if Muramasa somehow ends up getting killed. He has the original corruption agent that turned that first band of horses into an undead nightmare. His father, Oda, obviously wasn’t privy to that little tidbit. If Muramasa is killed, he’d become the first kirin-kelpie in the world and the nightmare would begin all over again.
As written above, kelpies came in four flavors: unicorn-kelpie, pegasus-kelpie*, pterripus-kelpie, and the original flavor; horses. The two flavors of winged kelpies were permanently grounded since foals of either flavors were born with tattered or holey wings. From a certain height, they could glide but true flight is impossible. The horned flavors lacked the magic of their living counterparts, apart from the magic needed for their illusions. Kelpies aren’t considered true transformers since deception was all they could do to hunt their prey and continue the species. They can’t truly transform themselves the way capable beings were. To rest of the world, it didn’t matter what flavor they were. They were still part of the Kelpie Race and so beings didn’t make any distinction over the types.
A mare who found herself carrying kelpie spawn could actually strike a lucky break. Sometimes she may miscarry the foal or she would find a sympathetic being to kill the thing after it’s born. Even when they’re born, a kelpie foal is a danger to anything around it. It’s born with a voracious appetite (hence why survival rates among kelpie mothers is fairly low) and it uses its illusion power instinctively. A survival tactic a foal uses instinctively after birth is to appear as an actual living foal. It’s often enough to make the mare forget that it was conceived by a kelpie and she pays for that moment of weakness with loss of life or limb.
Should a mare walk away from a kelpie attack, carrying his foal or not, there’s always residual taint left behind. All mares who are used by a kelpie to carry his spawn have their reproductive organs permanently damaged. The birthing canal and those organs related to birthing continue to function until the foal is born, after which they are irrevocably damaged beyond healing. On magical beings like the unicorns, the taint can be a visible mark as well, depending on how hard she fought the kelpie’s inherent evil. It is most visible on the human form, as fur hides the mark.
Let’s use Queen Allianna of the unicorns for an example. She walked away from her encounter with Thanatos, the last kelpie, carrying his spawn. Anyone who’s read False Form knows that she was found by an alchemist, Nomad, who took her to his lab for experimentation. Nomad practically saved Allianna’s life. As part of his experiment to create a chimera that’s born through an organic body (as opposed to the test tube), Nomad cut Thanatos’ spawn from Allianna’s womb. That killed the fetus no problem. Because her body was already following the natural order of creating and carrying new life, Allianna was the perfect test subject for Nomad’s experiment. He withdrew some DNA from Allianna’s blood, spliced it with the other component DNA and implanted it into one of her eggs. That new chimeric egg would eventually grow into Phoenix, the first and only chimera that was truly “born”. Allianna carried Phoenix for a normal term and gave birth later on, after realizing she wasn’t carrying Thanatos’ spawn anymore when the three weeks was up. At first, she thought she miscarried the kelpie foal but as time went on, she kept having the same signs that indicated a normal pregnancy. By the time she realized she was carrying something else, Phoenix was born and taken from her by Nomad.
Even though she was no longer carrying Thanatos’ spawn, Allianna suffered the same damage to her reproductive system as all other victims of a kelpie attack. The process was slowed, thanks to a longer gestation period than the average kelpie’s, but Allianna was rendered unable regardless in the end. Because Thanato’s taint overruled her inherent purity, the taint appears as black veins spider-webbing across her skin and only visible in a human form as her fur hide it. Allianna, out of utter shame, abandoned her human form so she didn’t have to see the physical manifestation of the taint, a constant reminder of how she was defiled by a kelpie. Even when a being abandons their human form, the magic used to transform remains so it’s more a matter of never drawing on that power willingly. Allianna was badly wounded in the Spider-East War and the severity required that Seiryu force-change her into her human form so she could heal, revealing the taint that marked her as a kelpie victim. Between her last transformation and the force-change, Allianna hadn’t been seen in a human form for roughly eighty years.
*Pegasus-kelpies are NOT thestrals which have only appeared in the Harry Potter series. I consider thestrals to be a whole other can of worms, seeing as how thestrals can fly and are only visible to mortals who have witnessed and accepted a death. Pegasus-kelpies can’t fly and are quite visible to anyone with working eyes. Even with wings, they still resided in bogs around All World. There are also a number of physical differences between the two that I won’t get into but you can read up on threstrals on Wikipedia or a Harry Potter Wiki. Pegasus-kelpies are Exactly What It Says On The Tin: undead pegasi who are a sub-form of the actual water demon. As I consider threstrals to be the property of J.K. Rowling, I would never use them in my own canon. Any resemblance to thestrals is unintentional and only goes as far as the few similarities between the two goes: not far enough for a pegasus-kelpie to be considered a copy.