The Guardians of Magic
To understand the story, one must first know what a Guardian of Magic is. Magic seems to have a mind of its own sometimes and does not want to go extinct. There are rarities among magic, long lost and forgotten gifts that have been bestowed upon families and lost in the breeding line. Pure magic is neither good or bad, but when someone so evil as, say, Lord Voldemort is born with powers that can destroy the world, magic seems to take on its own defense against the extinction of itself. Because, in the end, even if Voldemort rid the world of muggle borns, he would continue to lust after power until he was the only one left standing. And that wouldn't be good for magic, would it?
A prophesy was formed three hundred years ago on August 9th, stating that there were to be born two Guardians of Magic to save the world from a dark power that would suck the world of all magic. Well, they would try at least. The two guardians would be the whitest jewel and the purest of black. No one knew what this meant until Albus Dumbledore discovered this prophesy lurking in the shadows of the Ministry of Magic in the Department of Mysteries. And it just so happened that he knew exactly how these two guardians would come about.
Guardians of Magic aren't born with many special gifts. They start out with a few, and as they grow older, their gifts seem to grow into a bundle, maybe more than they can handle. That's why when the two guardians were born, Albus Dumbledore made sure to send them to Hogwarts so they could be properly trained to handle themselves. This wasn't an easy task, as the Guardians of Magic could only be born using a special concoction called the Division Potion.
One day, Dumbledore was in his office at Hogwarts when he realized this. The Division Potion was supposed to be a mythological potion, and even if it was real, the ingredients weren't said to exist. But even if they did exist, the last ingredient was the blood of the maker, and the two fathers of the Guardians were going to be hard to obtain.
On the night Severus Snape, a death eater at the time, had had enough of Lord Voldemort, he came to Dumbledore in need for help in fleeing against him, and it seemed the Dumbledore needed help as well.
Albus's proposition was that Severus, an expert potionist, was to gather these ingredients in return for a job and place to live at Hogwarts, protection against Voldemort's supporters, even though Severus would still report back to Voldemort, turning himself into a double agent. Severus reluctantly agreed, after Dumbledore specifically telling Snape to tell the Dark Lord about the Division Potion. This seemed completely stupid in Snape's eyes, because if Voldemort would ever find out about the Guardians of Magic, he would immediately have them killed.
This was not the case, Dumbledore had replied sure of himself. Because Dumbledore knew that one of the Guardians of Magic would be none other than a Malfoy, the whitest jewel. And he needed Lucius Malfoy's blood to make one.
The other's blood was easier to obtain. Sirius Black's. The purest black.
Three hundred years after the prophesy was made, on August 9th, two babies were born using the potion. Sirius Black's child was a girl, named Kathryn Maradora (after the Marauders) Black. Lucius Malfoy also made a child named Jade as was predicted, being a blonde named after a jewel.
A year later, Sirius Black was framed by Peter Pettigrew for murder, leaving him to go to Dumbledore to take care of his child. And Dumbledore handed Kathryn off to the only man he knew who would take care of her in the ways she needed to be cared for. That man was none other than Severus Snape.
And that starts the story of the Guardians of Magic.