They heard McGonagall grumbling on the other side of the door, but she didn’t linger to hear more. Harry released a breath of relief when the sound of her shoes disappeared. With a flick of his wand, rather than silencing Snape, he placed a strong privacy ward on the office - Snape could scream all he wanted, and no one would hear him. He glanced over his shoulder at Draco and found a peculiar look on his face - a kind of nervous constipation.