In a closed urban fantasy, the magical world is secret and no one knows about it. In an open urban fantasy, everyone knows about it. So with a closed fantasy, you have to figure out how the world keeps itself secret, and with an open one, you have to figure out how knowledge of magic has altered the world we know.
Cassandra ClareJace flushed a slow, dark red. "It's not like that. If I thought it would help the Clave-but it won't. She'll just get hurt-" "Even if you thought it would help the Clave", Simon said, "you'd never let them have her." "What makes you say that, vampire?" "Because no one can have her but you"said Simon
Cassandra ClareClary: What are you doing here, anyway? Jace: 'Here' as in your bedroom or 'here' as in the great spiritual question of our purpose here on this planet? If you're asking whether it's all just a cosmic coincidence or there's a greater metaethical purpose to life, well, that's a puzzler for the ages. I mean, simple ontological reductionism is clearly a fallacious argument, but- Clary: I'm going to bed.
Cassandra ClareI wouldn't change it," Simon said. "I wouldn't give up loving you. Not for anything. You know what Raphael told me? That I didn't know how to be a good vampire, that vampires accept that they're dead. But as long as I remember what it was like to love you, I'll always feel like I'm alive.
Cassandra Clare