"But, I couldn’t stop thinking about that book you found," he glanced down at the book in his hand, and Harry finally read the title, "Alchemy, Ancient Art and Science’, "Did you know," Harry’s eyes snapped back to Draco’s, observing that Draco suddenly sounded like he was forcing back tears, "Did you know, that one of the theories about the philosopher’s stone... about the elixir of life, is that it works by borrowing time from the life of the drinkers’ alternative selves in different realities.