"My question," he continued, his slit-pupiled eyes boring into Draco, "is what you plan to do with the information you have gathered"
Draco stared. He was shocked into speech. "What"
"I am asking," his Master's voice was somewhat impatient, and it frightened Draco still further to think what the Dark Lord was capable of when impatient, "who you plan to tell"
When Draco still looked blank, the Dark Lord spoke again, advancing upon Draco menacingly as he did. "I have hidden the fact that Nagini's an Animagus for years. Even Dumbledore, who, I have no doubt, studied my life intently, could not have known her true identity. This information is most valuable. To whom are you going to sell it"
And Draco understood. His loyalty was being tested. "No one, my Lord"
The Dark Lord smiled. It was horrible to behold. "You know, I assume, of my power at Legilmancy"
Draco nodded, unable to speak. About what had he lied?
"Then tell me truthfully, for I will know if you lie: was Nagini correct about your prowess as a Death Eater"
Draco was about to say of course when he caught himself. Could he really kill? Dumbledore didn't think so. But what did Dumbledore know?
He knew Draco.
"I...I'm not sure, my Lord"
He feared his Master's wrath, and was surprised when the Dark Lord merely looked satisfied.
"An honest answer," he proclaimed. "I will have to test your mettle in the field"
Snape's insides twisted with guilt, remorse, and the knowledge that there had been no other option.
Dumbledore had known what would be asked of Draco, and he had prepared by telling Snape to make the Vow. Snape had done so readily, assuming that his mentor knew a way OUT of the Vow.
Snape had pleaded. He had gotten angry, nearly wept, but Dumbledore remained firm. It seemed that he wanted to make sure that his death was planned, staged; Snape was merely there to facilitate the abomination.
He couldn't understand why Dumbledore valued Snape's life over his own. Dumbledore was so important to the Order, and if he ended up being the one to fulfill the Dark Lord's hateful task (and he knew he would), he would be vilified by the Order, and would not be their agent anymore.
He made these arguments to Dumbledore, all to know avail.
He might not have gone through with it. Standing there over him, he wanted nothing more than to jump over the edge and hope that his impact was fatal.
But Dumbledore had begged. And with utter revulsion, Snape did what he had sworn he'd do.
That had been bad enough. But then Potter had the gall to call him a coward. Hadn't he just had to kill the man he admired most? Hadn't he just been forced to destroy the one person who had brought him back from the depths of darkness, the one who had shown him the light? It was too much! Potter could never have done it, and yet he had the nerve, the audacity, to call him a coward.
And yet, as he sat with his head in his hands, away from the fire and the Death Eaters laughing and showing off battle scars, he wondered if maybe Potter was right. Killing Dumbledore had saved his own life, after all. Perhaps...