Boredom

Justin stared at his sister as she performed. She looked lively, it was nice to see that expression on her face once in a while. He had gotten so used to seeing frightened faces that he almost forgot they could make other expressions. 

Seeing her smile almost made him want to smile back at her. Almost. 

He examined her movements and her mood. She had improved immensely since the last time he saw her play for them. Her amateur mistakes had been reduced to none and she finally looked like she was in her element. 

That was a big improvement. Especially since that instrument wasn't hers.