"Dragons don't only subside on flesh to survive, but on fire and magic too. But something happened when mine hatched on the Wall, and they pulled something from it. Not only do Winter, Stormstrider, and Bloodfyre now have some affinity to the cold and ice, but they also have a connection to the Wall and can directly feed on its magic. That's how they grew so fast in the first fortnight. Guess where Winter is now?"