The man knew him. Good. It saved having to introduce himself. And from the stiff was he was sitting, he had to be holding his wand under the table. Otherwise, it wasn't good form to keep one's hand hidden.
"Lupin."
He glanced down at where he approximated the wand was.
"There a reason you're pointing a wand at the Chief Auror?" he asked, his own hand dropping as well. As far as he knew, Lupin was firmly in the pocket of the Order of the Phoenix. Well, he was a member, of course, but a vigilante group was a vigilante group.
Even if the people they were fighting were murderers.