[The name makes her blink. Luna pauses, tilting her head from one side to the other as she looks at him. He does look a little familiar, but far too young to be the Lupin she knows.]

I didn't know Professor Lupin had a brother. [Because he was a little too old to be the professors' son.] Is he here too? I never did get a chance to say goodbye. He was an awfully good defense against the dark arts teacher.

[Especially considering she now had, y'know, Umbridge.]