Julie Kagawa said this quote
“ It is the iron. Grimalkin picked his way over a puddle, then leaped atop a fallen tree, shaking out his paws.This close to the false king's realm, his influence is stronger that ever. It will be worse once you are actually within its borders.Puck snorted.Doesn't seem like it's affecting you much, Cat.That is because I am smarter than you and prepare for these things.Really? How would you prepare for me tossing you into a lake? ”