"I’ve known him for seven years. And all the time I’ve known him, I’ve never seen him fall in love, never seen him even like anyone. He’d hook up with girls, sure. Girls always fell in love with him, but he never cared. I think that’s why Alec thought—It always worried me, and my mom, too—I mean, what kind of teenage boy never even gets a crush on anyone? It was like he was always half-awake where other people were concerned. I thought maybe what had happened with his father had done some sort of permanent damage to him, like maybe he never really could love anyone. If I’d only known what had really happened with his father—but then I probably would have thought the same thing, wouldn’t I? I mean, who wouldn’t have been damaged by that? And then we met you, and it was like he woke up. You couldn’t see it, because you’d never known him any different. But I saw it. Hodge saw it. Alec saw it—why do you think he hated you so much? It was like that from the second we met you. You thought it was amazing that you could see us, and it was, but what was amazing to me was that Jace could see you, too. He kept talking about you all the way back to the Institute; he made Hodge send him out to get you; and once he brought you back, he didn’t want you to leave again. Wherever you were in the room, he watched you…. He was even jealous of Simon. I’m not sure he realized it himself, but he was. I could tell. Jealous of a mundane. And then after what happened to Simon at the party, he was willing to go with you to the Dumort, to break Clave Law, just to save a mundane he didn’t even like. He did it for you. Because if anything had happened to Simon, you would have been hurt. You were the first person outside our family whose happiness I’d ever seen him take into consideration. Because he loved you."
-Isabelle Lightwood to Clary, City of Glass