Voldemort: Harry Potter. We meet again.
Voldemort: Yes. You see what I've become? See what I must do to survive? Live off another, a mere parasite! Unicorn blood can sustain me, but it cannot give me a body of my own. But there is something that can, something that, conveniently enough, lies in your pocket!
Professor Quirrell unwraps his turbine to reveal Voldemort's face on the back of his head.