When he was gone, Draco had half a mind to move, just because he'd been told not to, and he did shift a bit in his seat, eying the draught that Snape had brewed for him.
He drank it down a moment later, hoping that it at least eased something.
A moment later, he was sure he'd been tricked - his mark began to burn again, suddenly and viciously, and Draco screamed before he could stop himself. This burning was different than just the Dark Magic that had retaliated against the potion. This burning was angry.