Cassandra Clare said this quote

Goodness, that stuff rips like paper,” she exclaimed, reaching to pull her tank top off. She was halfway through the action when the door opened and Alec walked into the room.“Izzy, are you—” he began. His eyes flew wide, and he backed up fast enough to smack his head into the wall behind him. “What is he doing here?”Isabelle tugged her tank top back down and glared at her brother. “You don’t knock now?”“It—It’s my bedroom!” Alec spluttered. He seemed to be deliberately trying not to look at Izzy and Simon, who were indeed in a very compromising position.