Disclaimer: The universe of Harry Potter belongs to J.K Rowling.
Chapter 1: Divergence
Magic.
It's a curious thing.
Beckoning from the existence of man, magic has manifested itself in the most curious ways. It can be used to turn water into wine. For the more ambitious, it can help them become an animal that represents their inner personality.
Many use magic for common, household duties - cleaning the dishes, warming food, setting a table. Others utilize it for fighting one another; they use different spells to maim and injure their opponent. Further yet, magic is grasped by those who wish to learn more about its inner workings, attempting to understand how certain spells can neutralize gravity or create matter from thin air. In some cases, these scholars try to understand why some spells can force out the life force from beings or activate different synapses within the human body.
Then, there are the giants. Those who are so attuned to magic that they wield it symbiotically. Magic flows through their veins just as their heart constantly beats. Their control over this mysterious force is unmatched, and so are their uses of such power.
Many within this world remember how one such giant massacred millions in the magical version of the World War. Most also recall how that same giant was brought upon his knees by another; two humans with such power at their fingertips that they could be confused with gods. More recently, another giant came to be. Bringing upon darkness to a once mighty society, he was finally trumped on a late October night.
This tells the story of all that came to follow.
And how a new titan was born.
A man dressed in dark, black robes sighed as he finally opened the door. A door that he'd been trying to open for a very long time. Ever since he heard about his fate, and how it is was tied to a set of particular young infants, he'd been trying to twist the knob and set his eyes upon the world inside that humble, unsuspecting house.
After all, that house was the birthplace of a Harry James Potter.
Tom Riddle strolled quietly as he examined the scene around him. A beautiful house, really. Riddle examined the portraits of the young couple and child around him. He picked up the pictures of the two dancing on their wedding day, young Harry letting out hiccups as he tried his father's first attempt at applesauce, and the entire family posing for a shot to remember: Lily and James embracing each other as Harry climbed onto his father's head.
Riddle wasn't always a monster like many believed. He once had a family of his own - a wife. He met his companion shortly after he finished Hogwarts and journeyed down his path to create more Horcruxes and collect the heirlooms of the Founders. She changed him for the better. A talented wizard in her own right, Rose Riddle showed him the error in his ways, even accepting his past mistakes and instead looked at Tom as a brilliant, loving man. Those were the good days. They even were soon to have a child together as they quietly lived happily in a remote town. Tom Riddle moved away from hating Muggles to interacting with them. Tom Riddle moved away from destroying his soul in a search for immortality to embracing his humanity and cherishing the years he could spend. Tom Riddle wasn't a monster then, despite having been a killer in his teens. Rose Riddle changed all of that.
Until she died. Rose, peacefully drinking her afternoon tea in a small cafe, was oblivious to the danger that she was soon to face. A muggle robber, drunk and insane, took out his gun and pointed it at the customers within the cafe. His drunken mind failed to consider how the entire world would change as he hinged his finger onto his pistol, releasing a silver coated bullet onto Rose before she could even comprehend what surrounded her. As the bullet entered her body, she felt life leaving her body, abandoning her as she cried out to it. While the drunk criminal would be able to regain his wit in the coming hours and come to understand what he had done, Rose Riddle had no such opportunity, nor would the child budding within her.
Tom Riddle came to once again lead the path of darkness, seeking revenge for his own loss with bloodshed. Slaughtering muggle families and decimating wizards who looked to stand in his way, Tom Riddle was the perfect combination of hate and power.
Until he became privy to a prophecy that foretold his future. The prophecy boys, Harry Potter and Neville Longbottom, both stood in his way to utter and total domination. He knew that only one was the fated; he chose Potter for their own similarities they shared by blood. With that decision, Riddle wouldn't even start to comprehend how he would alter the lives of not just two boys, but the world itself.
Riddle carefully walked up the stairs, careful not to make a single creak. He had been alerted to the fact that this was the young couple's anniversary, and they had one of their mothers watching over little Harry for the night. Riddle finally reached the final step and began to hear the quiet cries of a baby within a room. Walking down the hallway, wand in his hand and armed with a stoic expression, Riddle opened the door and saw an elderly woman trying to get the baby to sleep by reading him a book. As the door slightly creaked, she quickly looked at the knob but was met with a silent burst of green light. Her frozen body tumbled to the ground dramatically, bringing the eyes of a suddenly quiet infant with her.
Harry looked upon this strange man in dark clothes with wonder and fear. Riddle stared into the child's eyes and muttered two words that would forever connect the two:
"Avada Kedavra"
The sickly green light seemed to appear in slow motion to Riddle, with each second feeling like an eternity. He counted down as the light passed through the air.
"3"
Harry bored into the bright, green color - not realizing that it would tear his soul from his body. He was reminded of the dragons he watched on his cartoons, and slightly giggled in remembrance.
"2"
As Riddle stared into Harry's unsuspecting, wide eyes, he was thrown back into reminiscence about his own child with Rose. A life that would never happen. A life that caused him to turn back to the darkness and preach destruction. A life that he had vowed to never remember ever again.
"1"
The crackling green energy, millimeters away from Harry's forehead, eager to have a new victim, suddenly stopped. Harry's eyes, the light green color that many fawned over, suddenly turned ice blue. The bolt originating from the Yew wand returned back to its master, tearing his soul out of his scar-laden body and into pieces.
One piece, as if a magnet, latched onto Harry's skull, creating a lightning bolt scar as it forcefully muscled through his unblemished, soft skin and entered his body.
And then the doors came crashing open.