Carrie Ryan said this quote

Not all monsters are filled with darkness.' She wanted him to understand this so badly that her voice trembled.He didn't even hesitate. 'This one is.'She allowed herself a moment to admire Tommy, the way he stood so resolute, like a knight charging after the monster. He just didn't get that this fight wasn't his to wage.'Exactly so,' she finally said.Of course Tommy would think she talking to him. He exhaled as though relieved and the start of a smile eased the tension around his lips. By the time he realized that she'd spoken the words to someone over his shoulder, it was already too late.