It made him feel indispensable and needed - even if the fact that Jocelyn didn't appear to care wheather he slept in her daughter's bed or not did underscore that Clary's mother apparently regarded him as about sexually threatening as a goldfish.

The past is nothing to [the young], not even another country as it is to the old, or even a nightmare as it is to the guilty.

Don't fight in front of the client, boys." Catarina implored in her sweet voice," or I will knock your heads together so hard, your skulls will crack like eggs

I know you feel inhuman, and as if you are set apart, away from life and love, but... I promise you, the right man won't care.

You have a dark heart in you, Valentine’s daughter,” he said. “You just won’t admit it. And if you want Jace, you had better accept it. Because he belongs to me now.

The missing stairs baffled Clary. What did vampires have against stairs? -Clary, pg.266-

Enough, both of you,' Clary said. 'You can't be complete jerks to each other forever, you know.' Technically,' said Simon, 'I can.' Jace made an inelegant noise; after a moment Clary realized that he was trying not to laugh, and only semi-succeeding.