The Boy-Who-Lived. How lies have fed your legend, Harry! Do you want to know what really happened thirteen years ago? Shall I divulge how I truly lost my powers? It was love. You see, when dear sweet Lily Potter gave her life for her only son, it provided him with the ultimate protection, I could not touch him. It was old magic, something I should have foreseen. But no matter, no matter, things have changed. I CAN TOUCH YOU… NOW! Astounding what a few drops of your blood will do, eh, Harry?
Harry Potter and the Goblet of Fire, Lord Voldemort