Beginning of Purity
Purity wasn't born, she wasn't made, but she wasn't a random occurrence either. She was formed by the Great Creator, just a little after her sister Corruption. While Purity was never a child in the way we understand, she was young and inexperienced. She and her sister were opposites by nature, and often argued and fought, but there were times when they could coexist and were happy. The Great Creator raised her and her sister, teaching them, showing them the many worlds (though there was less way back then), and telling them of their duties. The inhabitants of the worlds needed to learn and grow as well, for that they need to make decisions; for them to make decisions, there needed to be choices; and for there to be choices, there needed to be opposition in all things. Purity and Corruption were a part of that balance, speaking to their hearts and attempting to influence them one way or the other.
Purity saw her work as a duty and a natural need for the benefit of the worlds. Corruption saw it as a game, one that she might never win, but she could cause as much damage as possible. And with each new branch of the multiverse and each new world, the cycle would begin. Corruption would make tyrants and murders while Purity would help heroes and protectors rise to stop them. Over and over they went, across every world and throughout the ages. Each time the players were different, but the outcome was always the same, the light triumphs over darkness at least for a time.
Purity and Corruption, while the leaders of the conflict, were not alone in the fight. Others were chosen from the worlds to protect and watch over them, Guardians if you will, both for the light and the darks as well as those that were neutral. Purity loved visiting the Guardians of the different worlds, for they were the only ones she could truly interact with. For all her power, she could not directly intervene in the natural course of the worlds. She would help them and guide them in their duties. She cared for them; they were her family, her younger siblings.
But for all that, Purity was incredibly lonely as the ages passed. While she could visit the other Guardians, she could never stay. They had their worlds to watch after; she had to watch over every world, the entire multiverse. She spent most of her time alone, watching over the heart of the multiverse. While the Guardians could sympathize and comfort, they could never truly understand. Her sister cared nothing for her plight, wrapped up too much in her game. Purity would often visit her older brothers, Life and Death, for advice. They were completely neutral in the conflict between light and dark and would often help give Purity some perspective on her life and duties. And like her, they were unique in watching over the entire multiverse. While they might choose representatives on the different worlds, they were the true guardians.
Things finally started to change for Purity when the Great Creator informed her of a prophecy. A hero named Sonic of the Mobius branch of the multiverse would join with his world's chaos emeralds and become her Guardian. He would help her in her duties of protecting the multiverse and she would no longer be alone. Though it was still a few hundred years before he would be born, Purity was excited. She had taken many forms in her time, mostly human, but now she favored that of a mobian hedgehog. She never neglected her duties to the multiverse, but she spent extra time and care watching over the mobian worlds. It took time, but she finally figured out which one her chosen was to come from.
She watched it constantly and celebrated the day her chosen was finally born. She watched over him, guided him, and visited him and his family a rare few times. She protected him when she could, but there were many times when she could not interfere. Then finally the time came for him to join with the emeralds and embrace his destiny.
But Sonic rejected her at first, and it hurt Purity more than she cared to admit. She tried to convince him, but things just kept spiraling out of control. With the help of his friends, she was finally able to help him accept his destiny and he joined her in her home. He had trouble adjusting at first, often requesting to see and visit his friends and running around the palace and its grounds. Purity was little more than a teacher and advisor to him at the time, but that slowly changed.
Over time, Sonic began to talk to her and get to know her. They would chat in-between his missions and adventures, nothing ever important just the simple act of enjoying each other's company. They began to joke and laugh together, they began to be friends. Of course, he never forgot his old friends and would still visit them regularly, but now he didn't avoid or ignore Purity like he used to.
Purity knew she would never have his heart, for that belong to another, but she was fine with it. She had a friend and a protector, someone who understood the importance and difficulties of her duties. Someone that would be by her side throughout the ages and across the worlds. She was no longer alone and that was all that mattered to her. She was happy.