"Just because you trust someone you know with your secrets doesn't mean I should trust a perfect stranger with mine!" he hisses back. "Besides, you're living openly; anyone who wants to kill you or ask public questions," these are said in the exact same tone of voice, "has already had bloody yonks to find you if they wanted to! Anyway, since when have I ever been a civil adult??"
Ok, I've got him down to genuine concerns and self-depreciating jokes; that may have to do...