Disclaimer: I do not own Harry Potter J.K. Rowling does.
Prologue:
Lives are comprised of lost chances. Chances to accomplish a dream. Chances to make a friend. Chances to save another. Still, people often struggle to take the chances before them. They sometimes choose to skip out on those chances and in the end never complete their every desire. There are lost chances a person does not even know he or she had. There are chances a person lost and then moved on. And then, there are lost chances that bother a person's every waking moment.
There is an entity called the Creator of Universes. It looks like nothing. It smells like nothing. It talks to no one. It can only touch a person's soul. It can pull a person's soul apart. It can pull away the side that is greedy from the side that is selfless. It watches and waits until the right moment to use its powers. It does not care about the result of its choices, only that it completes its mission.
Sometimes the entity finds a person struggling to decide on whether to take a chance. Most times the entity ignores the person choosing between taking the chance and doing nothing. Yet, whenever the entity discovers someone so completely torn that the person became static, the entity separates the two warring factions of a person's mind. One part, that wishes to accept the chance, remains in the original universe, and the other side, that decides to forgo the chance, transfers into an entire new universe.
555
The boy he loved lips chewed on his own. The kiss Albus Dumbledore always dreamed of. Yet as his kiss with Gellert deepened, so much that both their tongues entangled with each other's teeth, Albus stopped mid-lick. Gellert continued on, probably thinking Albus would continue in a minute. But Albus did not. He stayed still and eventually Gellert relinquished Albus's lips.
Gellert rubbed his hand against his thighs. After sighing the sound that first attracted Albus to the boy, the mess of rough clangs with soft huffs, Gellert said, "Still feeling guilty, Albus. It's not your faults. Its all your brother's."
Albus partly agreed. If his brother had not interrupted their talk this morning Arianna would still be alive. Still a questioned lingered- who really killed his sister? Was it his furious spell, Alberforth's faulty Reducto charm or Gellert's dark hex? Albus may never know.
"Come on Albus," Gellert continued talking, probably hoping Albus would get over his sister's death. "This is our chance, lets return society to its proper order."
That was all Albus ever dreamed, for magic folk to regain their prestige instead of pretending normality and to punish those who contributed to Arianna's illness. But Albus was worried that if he continued on this path more innocent people would die.
Albus became locked in his own mind, fixated on Alberforth's scornful comments, Arianna's screams and Gellert's sweet, adoring remarks.
He was at impasse and the entity knew. That day the entity chose to divide Albus's soul. A risky move that gifted all Albus's good side to a world where he chose to make amends, later becoming the most renowned Headmaster of Hogwarts, and unleashed all Albus's bad side on the original world.
555
It was the middle of the year 1915 in the original world. Albus and Gellert were wreaking havoc. Many muggles died because of avalanches the two dark lords caused. Many wizards and witches struggled in the losing resistance. Muggles began to notice that magic somehow existed. The muggles feared the magic they witnessed.
Alone in the middle of the woods, a young girl settled beneath a tree. Her mind was far away from the ants running up her bare legs or the moths flickering around. Instead, Merope Gaunt considered the option before her.
She could continue to live with those who drenched her with water in the morning and pushed her around to do work all day. Or she could leave with Pollux Black into a world she did not understand. A frightening world where she would wander fighting along with the resistance against the darkest lords of history, where there was a possibility of dying every day.
A side of her was terrified of living without knowing what to expect. That side pulled her to stay with her father and brother. They may be treating her like a pigeon deserving a kicking, but they were home.
Another side of her ridiculed that notion and pulled her to leave. She experienced enough pain from abuse. She needed more days of receiving Pollux's smile and him gently brushing her hair while promising to always protect her. That side knew that she longed for happiness and that was what Pollux may offer, something her father and brother believed too distasteful.
The entity recognized that Merope was stuck, a statue, unable to open her eyes, so the entity created another universe.
The four universes ran parallel for many years. Albus and Merope never knew that their struggle those days caused an entity to create an additional universe. In fact, in those years, none of the people in every universe met anyone in the other universes. Each universe suffered or thrived thanks to actions every person took. Each world was stable.
Until one day, a group of four, from the world where Albus became Headmaster, accidently barged into the universe where Albus became a Dark Lord and Merope joined the resistance.
The event signaled the end of the universes running without a glitch. Both worlds contained their problems. One faced a war and the other faced too many feuds. The event changed the simple understanding of the reason the people fought.