Balthazar tried not to grin, but to be honest, he didn't try very hard. It was difficult not to be amused when Lily was hiding her laughter against his shoulder.
"Don't worry, Dave," he began after the boy had finished with the magic. He didn't want to throw off Dave's concentration, even if it was fun to tease him -- and he did make interesting faces, "It only took a few hundred years before I learned to stop making ridiculous faces."
Honestly, he liked to think he'd never made ridiculous faces, but perhaps he had when he was just learning as a boy.
The blue tint was a nice touch to the spell, he thought, and he did nod his approval now that he was finished -- for the moment -- teasing Dave.
"Is our task complete? I hear Dave has a lot of reading to do after all." So it hadn't been a very long moment, but his apprentice was just so easy to tease.