As the date of their departure back to Hogwarts drew nearer, he became more and more prone to what Mrs. Weasley called “fits of the sullens,” in which he would become taciturn and grumpy, often withdrawing to Buckbeak’s room for hours at a time. His gloom seeped through the house, oozing under doorways like some noxious gas, so that all of them became infected by it.