At first he worries he's hurt the poor boy somehow, but he realizes that that is not a pained noise. And that adorable blush might not be from the heat of the water.

"Oh-oh," Herbert singsongs, gently scratching his nails over Alfred's scalp. He takes his hands away for only a moment to pour shampoo into them, then starts working the lather through Alfred's hair with a grin. "I think I've hit upon something."