"Sir Henry then?" 9S asks, because due formalities ought to be observed unless he's told to dispense with them. It's good to know the man's name if he needs to identify him, but a unit such as himself certainly isn't on equal footing with the race that created his own.

Natural order, and all that.

"But that's my name," he carries right along, seeing nothing too strange about it himself. By now, though, he's aware he's the only android unit here. "Number 9, Type S. So 9S. But my friends call...called me Nines."