Roomie. What a loathsome word. He wasn't some -- child who shared a dorm with multiple students. This hotel made a mockery of them all. Severus wasn't so ill tempered that he didn't know that. This rooming situation was not Darcy's fault and there was unlikely to be any fixing it immediately. Snape had found out first hand what happened when you fell asleep in a spot you weren't assigned in.
No matter what, people would end up where they were supposed to be again.
But that didn't mean he had to like it either. Or that he had to be nice. "Darcy," he repeated with a disinterested sort of expression. "It's best we make...cohabitation rules and standards sooner rather than later."