Simon
Quote 1
"We all see what we want to see," [Simon] said quietly. (18.197)
This explains the power of magical glamor. When you look at a crumbling mental hospital, that's what you expect to see, and do. But there could be something else there.
Simon
Quote 2
"I was trying to make you jealous!" Simon screamed. [...] "You're so stupid, Clary. You're so stupid, can't you see anything?" (17.127)
Finally someone speaks his mind. Holding in these feelings for so long causes some volatile explosions of hurtful words. But hey, at least it's all out in the open.