Spoiler:
"Once the sith lords who chose to participate arrived on Nathema, he dominated their minds and crushed their resistance. He turned them into slaves to his will, forcing them to participate in the most complex ritual of Sith Sorcery ever attempted. Calling on the dark side, Lord Vitiate devoured them. HE fed on their power, absorbing it into himself, utterly obliterating all traces of his victims. Every man, woman and child on Nathema died that day. All insects, birds, plants. When the ritual ended, Nathema was no longer a world. Lord Vitiate sacrificed millions, stealing their life force to make himself immortal. Their deaths also made him stronger than any sith who had come before, and he ceased to be known as Lord Vitiate. On that day, the Emperor was truly born."
Definitely seems like exactly what happened to Nihilus on Katarr. One wonders if Nihilus would have been immortal had a wound not stopped him. One also wonders if the Emperor was born as a wound in the force and if another wound wasn't the key. But since the Exile had no effect on him, I guess not. It seems though that the sith emperor is an exact copy of Nihilus, without the side effects.
Edit: IT would also seem like Drew doesn't proof read his own work. If he was born a few decades before the hyperspace war, then how could he have been on a planet for a hundred years right up until Ragnos died and the GHW was initiated? And also, how could he be under 1,000 years? Damn you Drew.