Lilith: I told you to take care of the mundane captured by the Shadowhunters. What broke you free of my order?

Jace Herondale: Clary. You may be strong, but my love for her is stronger.

Lilith: So she’s the reason that I can only control you when you sleep. I knew Clarissa was dear to you. Why do you think I’ve been torturing you with dreams of you and Jonathan killing her? But clearly I underestimated the power of your love.

From Shadowhunters – Season 3 Episode 4: ‘Thy Soul Instructed’ (3×04)