You know what the worst thing I can imagine is? Simon had said. Not trusting someone I love.

I don’t know,” Mark said, looking down at his own long pale fingers tangled in the little boy’s brown curls. “He just – Julian left, and Tavvy fell asleep on my lap.”He sounded amazed, wondering.“Of course he did,” Cristina said. “He’s your brother. He trusts you.”“Nobody trusts a Hunter,” Mark said.

The Scholomance was a piece of Shadowhunter history come to life. A cold castle of towers and corridors carved into the side of a mountain in the Carpathians, it had existed for centuries as a place where the most elite of Shadowhunters were trained to deal with the double menaces of demons and Downworlders. It had been closed when the first Accords were signed: a show of faith that Downworlders and Shadowhunters were no longer at war.

Your trusting idiocy knows no bounds

Trust. It is like placing a blade in someone's hand and setting the very point to your heart.