Severus barely looked up from his marking when someone kocked on his door, simply called for them to enter. But when he heard Terry's voice, he put his quill down and raised his head.
"You are interrupting, Professor Boot," he said dryly, using the formal titles that he always did where students could hear. He gestured for Terry to enter and close the door. "But by all means, do so. I welcome the interruption. I am coming to believe that the students have become stupider under Slughorn's tutelage."
He watched as Terry came in and closed the door, his eyes narrowing as he got a good look at the younger man. He'd noticed that something was wrong when he'd come to fetch Faustus from Terry's rooms the other day but he'd been concentrating more on his errant son than Terry that day. But now that he got a good look at Terry, he could see that something was wrong.
He arched an eyebrow. "What brings you to my office, Terry?"