Shadowmarked Fae
The Shadowmarked Fae have been seen as cursed beings since the very beginning of when they came to be. Most fae innately have an affinity for the element of light, but with a rarity seen less often than once in a blue moon, there may be one fae born with an affinity for the element of shadow magic instead of light. By nature this means nothing towards the fae's parents or the fae itself, it was simply a babe born with shadow magic much like sometimes a human is born with red hair. Shadow magic is the ability to wield shadows and is quite versatile in its own right, however demons are most commonly the ones with shadow magic affinities.
However, by society, Shadowmarked Fae were seen as cursed creatures. A demon born in the bloodline and a stain to the lineage. Many babes born as shadowmarked fae were cast aside and left to die in the woods under the cover of night before they even have a few hours of their life to hold. Rarely are they even given a name in hopes that there is no record of their family line having a Shadowmarked Fae. In the case of history, they are written off as miscarriages or stillborns so they were never known to live to begin with.
There are some cases where the Shadowmarked Fae live. Such as with the second prince of the Royal Fae Family. The Krudozeic family was a proud line of powerful light magic users that had a penchant for fire magic as well, some even wielding lightning to their bidding. Bronzed skin, hair like spun gold, and eyes like miniature golden suns and wings that shimmered with light itself. They were proud of their line until a babe was born with pale purple skin and black hair like the night sky. In the place of the Krudozeic's prideful light magic was a powerful shadow magic that swirled with ice. Before even the wet nurses could realize what the new baby boy was, his mother ordered him to be cast into the woods as deep as could be.
The servants did as they were told and left the babe squalling to the moon underneath the trees that became warped in the night. Not even the adults dared venture far into these woods was the sun's light had faded. Though there was one boy who saw no fear in the dark of the night and he was the Crown Prince of Krudozeic, Arceros Krudozeic, who was a rising prodigy of both light and fire magic. Arceros picked up his newborn baby brother and brought him back home. He gave his brother the name Sanohm of the Krudozeic line. His mother was furious and nearly melted all the gold in the hall with her magic in as much a rage as she was. She took Sanohm from Arceros and bid the maids to more thoroughly dispose of the wretched whelp.
Again and again, Arceros thwarted his mother's plans to kill Sanohm until finally their mother gave up trying to kill the child. She no longer puts attempts on his life, but neither did she aid him with their father of much the same mindset.
No servant wanted to go near Sanohm for fear they or their children may become Shadowmarked as well. Arceros made Sanohm food, taught him, clothed him, and was essentially the one to raise Sanohm. As Sanohm became older, he was still seen as a cursed creature and shunned by most everyone in the palace and his country, even though he was their prince. It did not bother him much, since he prefered the company of books to begin with.
Many years passed and Sanohm began to travel with Arceros abandoning his duties in the palace and coming along with him. Not too long after they began their adventure together, they were found by a kitsune named Shikodori who took an interest in them. A spell in the night and suddenly they found themselves unable to resist hanging onto every word Shikodori said with an uncontrollable urge to follow his every order. This was the start of the path of Sanohm and Arceros on the way to becoming part of the twelve Demon Princes in servitude to the Demon King Shikodori.
Thousands of years later, the image of Shadowmarked Fae has become not as stringent as there are more practitioners of shadow magic and thus a wider understanding of the magic. This was also greatly aided by a few Shadowmarked Fae figuring out a long range transportation system using shadow walking that any person could use even if they did not have an affinity for shadow magic. This made trade between long distances far more safe even if the merchants were apprehensive at first.
Sanohm is still one of the most well known Shadowmarked Fae as he still holds onto his title as the Demon Prince Frostfang, God of Desire. His balanced treatment of all made many people ease on the prejudice against Shadowmarked Fae, especially within the city he ran before the Demon Prison was made. Before the arrival of The Radiant King, God of the Sun and God of Healing, Sanohm and Arceros ran a school to teach people how to heal with stitching and light magic. Stitching was taught by Sanohm since it was a type of magic anyone could learn to heal with if they had the aptitude to learn it and Arceros taught those with a healing oriented light magic how to heal many injuries and even illnesses. While it is still very frowned upon to give any reverence to the Demon Princes, there are many Shadowmarked Fae and academia students who give a prayer to Sanohm for his survivability and his wide breadth of knowledge since his title Prince of Desire is more based off his desire for knowledge than carnal desires, though he was known for those as well.


Man, Arceros is the only reason why I don't think this entire society should have been burnt to the ground.
Too low they build who build beneath the stars - Edward Young
They are a lot better in recent years lol Nowadays it's more superstition, I suppose is a way to put it. Some believe it, some don't care and see what you have done more than what you are ( fae are still notoriously judgmental though, especially towards demons)