Tonks gave him her best attempt at a real smile. It was good to be polite, in the very least. She stepped a bit away from the parenting section, which is where she was headed, not needing anyone to question why she was getting those sorts of books, especially someone from work. The longer work remained unaware of her current condition, the better.
"Caleb, that's right. How is your training going? Are you enjoying it? Hit Wizard...it's a hard job. I admire those who can do it." Not that being an Auror wasn't hard, but it wasn't so morally difficult. Or it didn't used to be, the ministry was changing now adays.
His question made her frown almost guiltily, really not wanting to reveal the books she was in here to find. "Ah... yes. Something to read. Just browsing, I suppose, you know."