Thanks to wonderful Ninja for Beta-reading :)
Quirrel was leaning over the body. It was not dead . . . yet.
Inside his head, he could hear the voice of his master. Kill it
Quirrel's body was shaking as he approached the innocent animal. Innocence seemed so fast away. Something he longed. But those were thoughts he must not think if his master was present. He swallowed hard and grabbed the animal's neck with his hands. He squeezed all the breath out of it. The creature panted as his hands pressed against its throat.
Quirrel panted too. The next second, he could feel his master in his head again, impatiently saying: Kill it.
"Yes, master. Right away, master," he murmured, gasping. He pushed against the unicorn's head and throat several times and watched as it panted, taking its last breaths.
Quirrel started feeling like an animal himself. The soul he had squeezed out of the unicorn – it started taking over his body, but it wasn't the pure, innocent soul of the unicorn. It was a black soul that penetrated his body. The soul seemed to push him backwards, and he found himself lying on the ground. He was red in his face and looked exhausted.
Don't waste time, drink it!
"Yes, master," Quirrel whimpered, sitting up. In his pocket was a knife, and with it, he cut open the throat of the animal, causing the blood to pour down the white pelt. The hair turned from white to red. Quirrel swallowed difficultly. He did not dare to imagine the blood running down his throat. He bent forward over the animal's neck. His head hurt, and he felt a bit sick by the sight of the blood. He tried to shut out his own feelings and thoughts as he jabbed his teeth into the unicorn's skin. For a second, he felt nothing but pain, but then the bad taste of the blood touched his lips and tongue.
Everything in Quirrel's body wanted to move away, to draw back, to leave the unicorn, but Voldemort pushed him forward. He swallowed the blood and ignored the sick feeling in his stomach and head.
He ignored the feeling of everything inside him hurting.
Always think of your master, never think of yourself.
That was the rule Quirrel recollected with every drop of blood that touched his lips. He had a feeling that the blood would kill him. But he forced himself to continue, or more accurately, the Dark Lord forced him.
He did not dare to think the wrong thoughts when his master was with him. He kept drinking. The blood did not kill him, but, inside him, he could feel the Dark Lord gaining strength. And then he realised that his master was on the move. Soon, too soon, he would rise again. And it would be him, Quirrel, who helped him. He was the Dark Lord's servant, now and forever.