"Oh, so you went to school with Severus - and Regulus, I assume," Gaius said, his smile widening as he looked at Barty. Barty looked almost alarmed, and Gaius sighed with humor, holding up his hands in a gesture of surrender. "I promise I'm less... um, intense than my darling brother. Serenus is Severus' twin, by the way, so don't wonder if you're seeing double. We didn't grow up together, which is why you wouldn't have known if you went to Hogwarts. We reconnected as adults, though, and happily enough we're now all working together. I was a professor at Hogwarts myself until recently, though."