Another possibility is that they could be a new group of dark wizards who emerge after Voldemort's death. They believe that by raising Harry, they can create a new order in the wizarding world. They might not be as well - known as the Death Eaters, but they are equally, if not more, dangerous.
In such a fanfiction, Harry would likely have a very different personality. Instead of being the kind - hearted boy we know, he could be cold and calculating. Maybe he'd be more of an anti - hero. He'd probably have a lot of internal conflict, torn between the values he was born with and the ones instilled by his killers - turned - caretakers.
Since it's an 'untold story', it's hard to say exactly who the killers are. But they could be serial killers, or those who committed heinous one - time crimes. They might come from different parts of the world, with different motives for their killings. Some could be motivated by greed, while others might be acting out of some sort of mental illness or personal vendetta.
The real killers could be a group of people who were part of a larger conspiracy. They might have been working together to eliminate certain individuals or groups in order to further their own interests. For example, if there were competing business interests or power struggles, they could be the ones behind the killings. They may have used underhanded tactics like poisoning or staging accidents to achieve their goals without getting caught easily.
In the real story of 'Killers of the Flower', the principal killers were white individuals. The Osage had significant oil wealth, and these men, desiring that wealth for themselves, resorted to murdering the Osage people. It was a case of extreme greed leading to heinous crimes. There were also likely some people who were involved in covering up these murders or were complicit in some way in the overall scheme to take the Osage's money.
The killers in the Columbine High School case were Eric Harris and Dylan Klebold.
Perhaps it could be Thor from Norse mythology. Thor is the god of thunder. So, Harry could have the power to control lightning or storms. He would be a very formidable wizard with such powers. His Hogwarts years would be full of situations where he uses these thunder - related powers to solve problems or fight off enemies.
I'm not sure specifically who the killers were in 'Pretty Little Killers: True Story' without more detailed research.
It could be Athena. Athena is known for her wisdom in Greek mythology. She could pass on her wisdom to Harry, making him not just a powerful wizard but also a very wise one. He could use this wisdom to solve problems in the wizarding world in a more strategic way.
Well, in some fanfictions, it might be a more abstract or self - created god - like being. However, a popular choice could also be Odin from Norse mythology. Odin is known for his wisdom and power, and raising Harry Potter would give the story a whole new Norse - influenced magical flavor. Harry could learn different forms of magic related to Norse runes and such.
Perhaps 'y' is a relative of Harry's that was thought to be dead. This relative could have a unique magical heritage that they pass on to Harry, making him even more powerful. For example, if 'y' was a distant cousin from a line of powerful seers, Harry might develop some precognitive abilities.