Tom Riddle sat on his throne of ebony and sighed a sigh of regret.
Yes, Tom Riddle, not Lord Voldermort. Contrary to popular belief, Tom was not Voldermort, and Voldermort was not Tom. Rather, they were reflections of each other- or, perhaps shadows would be a more accurate term for their form of existence.
You see, Tom Riddle did not die, nor did he transform from delving too deeply into the Dark Arts, or any of the other rumors floating around in such abundance. Instead, Tom had experienced a great loss- a loss that was too great, it seemed, for his already abused and fragile mind to handle. So, to deal with his grief, he had performed a spell to separate himself from it. Only, something went wrong.
The spell was supposed to destroy his misery, his dark reflection, once the separation was complete. Instead, it had formed into its own entity- and stayed. At first, it was only a small voice in the back of his mind, easy enough to ignore. But over time the voice got stronger. Over time, Tom got weaker.
We should kill them for what they did to us, for what they did to him…
Tom had been in love once. The foolish 'Light Side' had taken that away from him.
We couldn't protect him. They didn't even have the decency to kill him. He's still alive, you know, with no idea that we exist, living with those horrid creatures…
Eventually, the reflection had taken over. It still needed Tom to survive though, so his essence was locked away in the back of his consciousness. He had become the voice in the back of Voldermort's head, for that was the name this shadow of twisted grief, loss, and rage had chosen for itself.
If his soul mate were here, his light, he would be saved. But the Light, in all of its infinite foolishness, had tried to 'save' his light- and in doing so, it had doomed all of them. His light was so pure, so innocent… Tom reveled in the memories he was able to call forth during his few lucid moments, when he was in control of the deformed, monstrous body that had become his own. But the Light had seen his pure love, and believed that Tom (the supposed 'darkness) was tainting him; and so, they took him away.
'To save him,' they said. When his light tried to go back to him, they had only shaken their heads sadly and murmured, 'Poor boy; the monster has cursed him.' And so, still in the name of saving his love, they had performed a spell to reverse his age, hoping that growing up again without his other half would keep the light pure and untainted. When they performed that spell, the soul link had been severed; it was still there now, like an open wound. His other had it too- the shadow wound that would never heal. When that link was broken, so was Tom.
Which was why he had just disbanded the last of his Deatheaters, with a healthy dose of Memory Charm all around. He knew that he wouldn't survive the Last Battle. Because even though the other had been taken from him long ago and no longer remembered him…
How could he kill his soul mate?