Mark found it pretty easy to play the piano, the notes came naturally it was the feeling that he wasn't used to. He played with emotion of course, and passion. A great deal of passion and that much was obvious but there was a different sense of emotion that seemed to be pouring into each note. Something that confused Mark, it had caught him off guard as he played. His mind wondered on how to deal with such a feeling. Trying to ignore it seemed like the best way to do so at least for the time being. He didn't understand human sensations the way even Shadowhunters did, and that was saying something.
His fingers came to rest on his own lap once he'd finished the song, looking down at the keys as though they had been enchanted, but he knew they were not. Looking over to Jace, he smiled softly. Clearing his throat a little he started to allow the glamours cover the pieces of his vulnerability up again. Feeling bare, feeling exposed a bit. "Thank you, it's been a while since I've really been able to actually play." He looked over Jace for a moment and wondered so much about the other and then knew not where to start as well.