Well, because Callum's fic, especially, stands out in his unique use of imagery and vocabulary, and was quite stunning in its plot. But I've found often that longer fics don't do as well, so I really didn't expect to win.

Thank you! I'm tickled! I've been doing really well since April: a Wraeththu winning, and a couple of older HP fics commemorated over at TQP thanks to Wolfie. ;)