(that’s the Finnish word for Albino)
This is a starter lore, readily adaptable to any fantasy writing.
Once upon a time, the Albiino of Finland were a human sub-species with albino traits – the lack of pigmentation. But they were not genetic rarities but rather an actual sub-species that bred with each other exclusively and all had the same distinctive features. Not only that, they had some powers verging on the supernatural and superhuman.
The Albiino were known for being primarily demon-hunters, but also vigilantes. Although most of them just led regular lives, domestic and silversmithing and hunting.
Yes, you are picturing Geralt, but they are more like Elrond.
Unfortunately their mortal enemies kill most of them, centuries ago, and the rest outbred until their occurence was as rare as human albinos. Their enemies forgot about them over time.
Even so, genetic throwbacks mean that some turn up here and there. An organization seemingly simply researching albino genetics is actually a front for a group trying to bring back the sub-species. They discover their own kind via DNA and put effort into recruiting their fellow Albiino during childhood or early adulthood, always watching over them.
Once recruited, the rules are simple. Fight for good, fight demons, and only have babies with other Even so, genetic throwbacks mean that some turn up here and there. An organization seemingly simply researching albino genetics is actually a front for a group trying to bring back the sub-species. They discover their own kind via DNA and put effort into recruiting their fellow Albiino. And never be discovered.
Consequently they disguise themselves with coloured contacts and died hair, and they basically present themselves as tall, skinny goths.
Why now? Well, DNA, contacts and sunscreen make it all possible in the modern era.