Portion in italics taken from Matthew Stover's Revenge of the Sith.
Anakin looked from the dead hand on the ledge to the living once above him, and what he saw there chocked him like an invisible fist crushing his throat.
The hand on his shoulder was human.
The face… wasn't.
The eyes were cold and feral yellow, and they gleamed like those of a predator lurking beyond a fringe of firelight; the bone around those feral eyes had swollen and melted and flowed like durasteel spilled from a fusion smelter, and the flesh that blanketed it had gone corpse-gray and coarse as rotten synthplast.
Stunned with horror, stunned with revulsion, Anakin could only star at the creature. At the shadow.
Looking into the face of the darkness, he saw his future.
"Now come inside," the darkness said.
After a moment, he did.
At the fringes of his conscious was a voice from his dreams. No, Anakin, no!
"Qui-Gon?" Anakin whispered, taking a step back. He was in shock. He wasn't thinking straight, couldn't make sense of what had just happened. He glanced again toward the window ledge where seconds before Mace Windu had tumbled to his death. Why hadn't he stopped him? Helped him?
There will never be balance, the voice said. Not this way…
"Anakin," said the darkness, insistent now.
Anakin couldn't bring himself to respond. The galaxy felt as though it had been rent at the seams. The force itself seemed to shriek in outrage. There was no balance. There was only the darkness, stretching like a black hole, swallowing the fabric of space and time and everything he had ever known so that it all ceased to exist. The pull was inescapable.
Soon he would pass the event horizon and be lost forever.
But he had not reached the event horizon yet. It was not too late to fight.
"No." He barely recognized his own voice, distorted. "No!"
"As you wish," Palpatine said.
The fallen Jedi Master's lightsaber sprang from his dead hand and pierced Anakin's heart with the intake of his last breath. Anakin Skywalker fell backwards off the window ledge with one thought, one memory, and one dream of all that could have been.