"The very bricks and mortar of the house are full of spells and enchantments," Hermione explained. "They carry links right back to Harry’s own energy, so he knows everything that goes on around here, but the effect goes the other way, too. So when his emotions spike, the house reflects to change that. The enchantments are attuned to Harry, and now I am attuned to him, too ... so I can feel them as well."