Raphael's hand tightened on the hilt of the knife. His knuckles were white. He spoke to Magnus. "I have no soul," he said. "But I made you a promise on my mother's doorstep, and she was sacred to me.""Santiago- " Sebastian began."I was a child then. I am not now." The knife fell to the floor. Raphael turned and looked at Sebastian, his wide dark eyes very clear. "I cannot," he said. "I will not. I owe him a debt from many years ago.
Cassandra Clare, City of Heavenly Fire
city-of-heavenly-fire, debt, magnus-bane, mortal-instruments, raphael-santiago, sacrifice