"I have been starting to look at this in a new way," Harry explained. "That this whole thing is like a disease ... a virus ... a Weasley virus. I think that Ron’s dominance over you wasn’t confined to his fists and spells, but it’s in the very sensory reactions you have to him. You tremble at the sight of him, recoil when you hear his voice, get nauseous if you pick up on his scent. And I’m betting that the feel of his magic has the same effect. Not only that, but that the element of the Weasley Family magic inherent in his own merely amplifies the sensation."