Matthew has a habit of getting his heart broken. He seems to prefer a hopeless love.
-- Lucie Herondale (Chapter 1: "The Bright Web")

Importance: Lucie here foreshadows the unrequited love that Matthew grows to feel for Cordelia Carstairs in Chain of Iron. Though she here refers to a past lover of Matthew's, her words demonstrate that Matthew is a vulnerable character prone to falling in love and thus often the victim of betrayal, heartbreak, and rejection.

It seemed it had never occurred to her mother -- and would not have mattered to her if it had -- that just as it was a torment to love, it might be a torment to be loved. To be loved, and know it was not real.
-- Grace Blackthorn (Chapter 3: "Bitter and Sweet")

Importance: Grace's thoughts on the matter of love demonstrate just how unprepared for love she is and just how false her relationship with James has always been. She confesses to herself that the relationship is...