The diminutive makes Arthur's eyes widen a little in surprise, and the way his cheeks turn a little pink has nothing to do with the heat and everything to do with the slightly flustered sputtering as he glances away.

The turn of topic to John again is a blessing, and he leans into it perhaps a little too quickly, clearing his throat briefly. "A-actually, John, that- might not be a bad idea, after all. The only way to get used to your body is by using it, after all, this would certainly help speed that up."