"For if we assume for a moment that you are Alchemical Mercury, you would have been searching for that base matter to join with, to achieve your fundamental life desire ... and you found it in Harry, via a toad. You may have been searching for an actual creature but, in reality, though you couldn’t possibly have known it, you were actually looking for Harry. And the alchemical forces led you right to him, made sure it happened ... ensured that the White Queen would meet her Red King."