It was infuriating him, then. Theodore was inwardly somewhat pleased, but remained outwardly calm and unfazed - and more than that, unimpressed. The sight of the Dark Mark had no effect on him, as Blaine was presumably hoping. He felt a bit of disgust at the way the other man operated through fear and threats, expecting everyone to bend or break under his stare. It had probably been a while since he'd met someone who dared to stand in his way, as Theodore was doing now. Perhaps it had never happened to him at all.
Cold logic, that was all he needed. Theodore could be a very empathic, compassionate person, but he'd had a few moments to shut himself down before opening the door. Which he probably shouldn't have done (opening the door, that was, not shutting himself down - that had been a very good idea) because the satisfaction of watching this man attempt to intimidate him unsuccessfully would probably be worn off as soon as he saw Tracey. This was affecting her much more than him, of that he had no doubt.
"I don't need anyone to protect me from you, nor do I need your advice," he said. "But it's kind of you to take the time to warn me." This time he did move to close the door, with a polite smile that did not reach his eyes. "As I've said repeatedly, I'm very busy."