Disclaimer: J. created Harry Potter and owns all(?) rights. The movies might belong to others, but no matter. I don't earn anything by writing this or having you read it, so enjoy it for what it is. Free fan stuff! Hehe. Oh, and this is true for any future chapters as well.
One life for Another
– Chapter 1
In his final moments, the dark lord felt a wide array of emotions. He was elated for killing his nemesis, he felt chocked when discovering that he had failed again, he felt fear for the short moment his imminent death approached and lastly he felt the relief of knowing he had a backup plan already prepared to go in effect.
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In his Hogwarts days the dark lord, from now on known as Tom, had come across the concept of Horcrux'es in one of the books in the library. When asking his head of house for more information, all in his so far secret quest for immortality, he got the distinct impression that further inquiries would be frowned upon. For his own sake he decided to leave it for after graduation. The problem with this was, Tom was only a sixth year student. He could no longer play with Slytherins monster, and his schoolwork wasn't exactly challenging. He was bored out of his mind, and he needed to be careful to avoid I-Knew-You-Were-Evil-The-Moment-I-Saw-You professor Dumbledore's suspicious eyes. And they were everywhere.
So he focused on something relatively safe, and yet surprisingly interesting.
Sacrificial rituals.
As he read, studied them really, for the next year and a half he found that they all had a few things in common. One, they where more or less only used by light wizards. Two, and this was likely the reason for number one, they all required a sacrifice of equal value from the one/es who initiated them. Three, their effect could never go further then the moment of completion. All in all, they were rather useless. And this was the reason Dumbledore left the boy alone for the rest of his days in Hogwarts.
Tom wondered for some time if these rituals could be used to become immortal. But, to manage it, you would have to find something of equal value and that wasn't so easy.
Theoretically you could save someone's life once, but only at the cost of your own life. One life for another. And only ones, meaning – if someone tried to kill someone you cared about, and you gave your life to save this persons life, then all the murderer had to do was try again and he or she would succeed. Useless, even if he could find enough people to give their life for him.
Tom didn't like giving up though. So for years he always kept the knowledge of these rituals in mind, on late evenings he dedicated some time to finding a use for them and in time it came to him. There was no rule stating that you had to be aware of your participation in a ritual. Only that you had to be willing to make the sacrifice. Therefore, all he had to do was find something everyone would give up and he could gain something of equal value. He then created a ritual, its wording quite ridiculous according to himself, ridiculous, but necessary.
He realized that not all people would give up their life for the same reasons, and especially not for a complete stranger, so what he did was making not just himself target for the ritual, but everyone. Every living being on the planet needed to be targeted by the ritual.
The words he had to read was numerous, they even filled a small book, but once it started it would go on until all of the required conditions had been fulfilled. For most beings, this ritual would have little effect. All they had to do was give up their life so that they could live it again. Others gave their life so that people they cared about could have another chance. But a few, and these where the real ones Tom wanted to target, would give their life because they didn't want it. The power of each of those lives was at his disposal.
He could not become completely immortal this way, and he didn't try, instead he chose to send his own memories back in time giving himself a second chance together with the rest of them. Unlike the rest of them though, he would remember.
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One life for another was the rule. All lives in existence on earth at the moment of the dark lords demise was sacrificed, and from their sacrifice the people from the past was given life yet again. For some, age and wisdom was traded for youth and curiosity. Many gave their life so that older relatives could come back and live their lives again. Because of all the sacrifices made, Tom had managed to alter all the tangled purposes a bit. The magic of the ritual had been so confused that it went down to basic. And Tom knew the basics. For this ritual, one specific person's desires meant little. One life for another.
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To be continued.