You guessed? You must have been pretty sure, considering you could have killed me." "I was ninety percent sure." "I see," Clary said. There must have… - Cassandra Clare

You could not tell a potential customer, expecting a learned and ancient magician, that you were not eve fully grown. Magnus had started lying about his age young, and had never dropped the habit. It did get a little embarrassing sometimes when he forgot what lie he'd told to whom. Someone had once asked him what Julius Caeser was like, and Magnus had stared at him for much too long and said, 'Not tall?'

"Is standing by the window muttering about blood something he does all the time?" asked Simon.
"No," Jace said. "Sometimes he sits on the couch and does it."

"Sebastian just smiled. “I could hear your heart beating,” he said softly. “When you were watching me with Valentine. Did it bother you?”
“That you seem to be dating my dad?” Jace shrugged. "You’re a little young for him, to be honest.”
“What?” For the first time since Jace had met him, Sebastian seemed flabbergasted.