"Ah, another cultural gap bridged." Mary says solemnly, leading them to a little corner-shop. "So is it sweet?"

She grabs milk, and then a few bags of sweets. If she gets bored she can just spend the evening seeing how many she can plant on Harry before he leaves. (Because the idea of him taking off the hoodie and scattering Smarties or Skittles across his scary flatmate's hardwood floor makes her giggle.)